Common use of Trust Clause in Contracts

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C-X Notional Amount as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 Class C-X Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C-X Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C2-X Notional Amount CB-4 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 31,569,066.00 Class C2-X CB-4 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X CB-4 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 31,569,066.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C2-X Notional Amount CB-5 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 31,022,740.00 Class C2-X CB-5 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X CB-5 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 31,022,740.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C2-X Notional Amount CB-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 149,937,994.00 Class C2-X CB-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X CB-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 149,937,994.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C2-X Notional Amount CB-6 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 41,289,416.00 Class C2-X CB-6 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X CB-6 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 41,289,416.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C1-X Notional Amount A-4 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 59,304,107.00 Class C1-X A-4 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C1-X A-4 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 59,304,107.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C1-X Notional Amount A-1 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 13,552,800.00 Class C1-X A-1 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C1-X A-1 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 13,552,800.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C3-X Notional Amount CB Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 37,805,200.00 Class C3-X CB Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 6.500% Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C3-X CB Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 37,805,200.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C1-X Notional Amount A-5 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 16,001,326.00 Class C1-X A-5 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C1-X A-5 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 16,001,326.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C4-X Notional Amount CB Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 29,539,800.00 Class C4-X CB Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 7.000% Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C4-X CB Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 29,539,800.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C2-X Notional Amount CB-7 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 3,753,584.00 Class C2-X CB-7 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X CB-7 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 3,753,584.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C2-X Notional Amount CB-1 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 24,424,200.00 Class C2-X CB-1 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X CB-1 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 24,424,200.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. The Class 1-A-7 Certificates will provide credit support to another Class of Certificates, as described in the Pooling Agreement. WMALT Series 2005-7 Portion of the Class C1-X Notional Amount A-7 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 1,000,000.00 Class C1-X A-7 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C1-X A-7 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 1,000,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. The Class 2-CB-2 Certificates will provide credit support to other Classes of Certificates, as described in the Pooling Agreement. WMALT Series 2005-7 Portion of the Class C2-X Notional Amount CB-2 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 4,195,000.00 Class C2-X CB-2 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X CB-2 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 4,195,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C1-X Notional Amount A-8 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 4,215,000.00 Class C1-X A-8 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C1-X A-8 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 4,215,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C1-X Notional Amount A-2 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 50,000,000.00 Class C1-X A-2 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C1-X A-2 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 50,000,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 1,897,569.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August 1, 2005 First Distribution Date: September 26, 2005 Last Scheduled Distribution Date: September 25, 2035 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 1,897,569.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August April 26, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 3 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 2,059,478.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August April 1, 2005 First Distribution Date: September 26May 25, 2005 Last Scheduled Distribution Date: September May 25, 2035 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 2,059,478.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26July 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 6 Portion of the Class C2-X Notional Amount A-2 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 46,775,666.00 Class C2-X A-2 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August July 1, 2005 First Distribution Date: September 26August 25, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X A-2 Principal Balance as of the Cut-Off Date: $0.00 Class C46,775,666.00 Cede & Co. Registered Owner WASHINGTON MUTUAL MORTGAGE PASS-X Notional Amount as of the Cut-Off Date: $14,369,296.00 THROUGH CERTIFICATE Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26March 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 2 Portion of the Class C2-X Notional Amount A-2 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 50,336,000.00 Class C2-X A-2 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August March 1, 2005 First Distribution Date: September 26April 25, 2005 Last Scheduled Distribution Date: September April 25, 2035 Class C2-X A-2 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 50,336,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26November 29, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C2-X Notional Amount A-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 73,950,000.00 Class C2-X A-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C2-X A-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 73,950,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26March 28, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 2 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 1,271,629.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August March 1, 2005 First Distribution Date: September 26April 25, 2005 Last Scheduled Distribution Date: September April 25, 2035 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 1,271,629.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26May 25, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 4 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 2,742,845.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August May 1, 2005 First Distribution Date: September 26June 27, 2005 Last Scheduled Distribution Date: September June 25, 2035 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 2,742,845.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August April 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 3 Portion of the Class C1-X Notional Amount CB-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 356,447,000.00 Class C1-X CB-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August April 1, 2005 First Distribution Date: September 26May 25, 2005 Last Scheduled Distribution Date: September May 25, 2035 Class C1-X CB-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 356,447,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26February 25, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 1 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% $912,192.00 Cut-Off Date: August February 1, 2005 First Distribution Date: September 26March 25, 2005 Last Scheduled Distribution Date: September March 25, 2035 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 912,192.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26November 29, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C2-X Notional Amount A-10 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 597,363.00 Class C2-X A-10 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C2-X A-10 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 597,363.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26November 29, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C1-X Notional Amount CB Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 62,532,200.00 Class C1-X CB Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 6.500% Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C1-X CB Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 62,532,200.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26May 25, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. The Class CB-8 Certificates will provide credit support to another Class of Certificates, as described in the Pooling Agreement. WMALT Series 2005-7 4 Portion of the Class C-X Notional Amount CB-8 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 3,576,900.00 Class C-X CB-8 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August May 1, 2005 First Distribution Date: September 26June 27, 2005 Last Scheduled Distribution Date: September June 25, 2035 Class C-X CB-8 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 3,576,900.00 Registered Owner Exhibit A CUSIP 939336 6D 0 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26October 27, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 9 Portion of the Class C2-X Notional Amount A-1 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 22,300,000.00 Class C2-X A-1 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August October 1, 2005 First Distribution Date: September 26November 25, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C2-X A-1 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 22,300,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26March 28, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 2 Portion of the Class C3-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 1,225,835.00 Class C3-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August March 1, 2005 First Distribution Date: September 26April 25, 2005 Last Scheduled Distribution Date: September April 25, 2035 2020 Class C3-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 1,225,835.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26November 29, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C4-X Notional Amount CB-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 117,923,200.00 Class C4-X CB-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September December 25, 2035 Class C4-X CB-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 117,923,200.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26February 25, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 1 Portion of the Class C3-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 Class C3-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% $224,290.00 Cut-Off Date: August February 1, 2005 First Distribution Date: September 26March 25, 2005 Last Scheduled Distribution Date: September March 25, 2035 2020 Class C3-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 224,290.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26July 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 6 Portion of the Class C2-X Notional Amount A-5 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 39,531,000.00 Class C2-X A-5 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August July 1, 2005 First Distribution Date: September 26August 25, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X A-5 Principal Balance as of the Cut-Off Date: $0.00 Class C39,531,000.00 Cede & Co. Registered Owner WASHINGTON MUTUAL MORTGAGE PASS-X Notional Amount as of the Cut-Off Date: $14,369,296.00 THROUGH CERTIFICATE Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26November 29, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C4-X Notional Amount CB-6 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 247,675.00 Class C4-X CB-6 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September December 25, 2035 Class C4-X CB-6 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 247,675.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26December 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company Trust or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 11 Portion of the Class C-X Notional Amount A-5 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 30,000,000.00 Class C-X A-5 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August December 1, 2005 First Distribution Date: September 26January 25, 2005 2006 Last Scheduled Distribution Date: September January 25, 2035 2036 Class C-X A-5 Principal Balance as of the Cut-Off Date: $0.00 30,000,000.00 Exhibit A CUSIP 93934F JA1 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 A-6 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26December 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company Trust or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 11 Portion of the Class C-X Notional Amount A-5 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 30,000,000.00 Class C-X A-5 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August December 1, 2005 First Distribution Date: September 26January 25, 2005 2006 Last Scheduled Distribution Date: September January 25, 2035 2036 Class C-X A-5 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 30,000,000.00 Exhibit A CUSIP 93934F JA1 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26November 29, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C5-X Notional Amount A Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 30,190,000.00 Class C5-X A Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September November 25, 2035 2020 Class C5-X A Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 30,190,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26May 25, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 4 Portion of the Class C-X Notional Amount CB-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 154,500,000.00 Class C-X CB-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August May 1, 2005 First Distribution Date: September 26June 27, 2005 Last Scheduled Distribution Date: September June 25, 2035 Class C-X CB-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 154,500,000.00 Registered Owner Exhibit A CUSIP 939336 5Y 5 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26May 25, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 4 Portion of the Class C-X Notional Amount CB-1 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 305,066,700.00 Class C-X CB-1 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August May 1, 2005 First Distribution Date: September 26June 27, 2005 Last Scheduled Distribution Date: September June 25, 2035 Class C-X CB-1 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 305,066,700.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26December 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company Trust or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 11 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 1,752,850.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August December 1, 2005 First Distribution Date: September 26January 25, 2005 2006 Last Scheduled Distribution Date: September January 25, 2035 2036 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 1,752,850.00 Exhibit A CUSIP 93934F JG8 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26November 29, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 8,882,888.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September December 25, 2035 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 8,882,888.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August April 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 3 Portion of the Class C2-X Notional Amount A-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 46,317,000.00 Class C2-X A-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August April 1, 2005 First Distribution Date: September 26May 25, 2005 Last Scheduled Distribution Date: September May 25, 2035 Class C2-X A-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 46,317,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26July 28, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 6 Portion of the Class C-X Notional Amount PPrincipal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 349,561.00 Class C-X Certificate PCertificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August July 1, 2005 First Distribution Date: September 26August 25, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C-X Principal PPrincipal Balance as of the Cut-Off Date: $0.00 Class C349,561.00 Cede & Co. Registered Owner WASHINGTON MUTUAL MORTGAGE PASS-X Notional Amount as of the Cut-Off Date: $14,369,296.00 THROUGH CERTIFICATE Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26May 25, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 4 Portion of the Class CD-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 2,019,462.00 Class CD-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August May 1, 2005 First Distribution Date: September 26June 27, 2005 Last Scheduled Distribution Date: September June 25, 2035 2020 Class CD-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 2,019,462.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26October 27, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 9 Portion of the Class C4-X Notional Amount A-2 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 50,000,000.00 Class C4-X A-2 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August October 1, 2005 First Distribution Date: September 26November 25, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C4-X A-2 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 50,000,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26October 27, 2005. Interest is not payable with respect to this Certificate. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 9 Portion of the Class C-X Notional Amount P Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 1,128,110.00 Class C-X P Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 0.00% Cut-Off Date: August October 1, 2005 First Distribution Date: September 26November 25, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C-X P Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 1,128,110.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26March 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 2 Portion of the Class C1-X Notional Amount A-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 281,002,000.00 Class C1-X A-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August March 1, 2005 First Distribution Date: September 26April 25, 2005 Last Scheduled Distribution Date: September April 25, 2035 Class C1-X A-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 281,002,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26May 25, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 4 Portion of the Class C-X Notional Amount CB-9 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 30,000,000.00 Class C-X CB-9 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August May 1, 2005 First Distribution Date: September 26June 27, 2005 Last Scheduled Distribution Date: September June 25, 2035 Class C-X CB-9 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 30,000,000.00 Registered Owner Exhibit A CUSIP 939336 6E 8 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26November 29, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 10 Portion of the Class C2-X Notional Amount A-7 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 25,000,000.00 Class C2-X A-7 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount 5.750% Cut-Off Date: August November 1, 2005 First Distribution Date: September 26December 27, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C2-X A-7 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 25,000,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26October 27, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 9 Portion of the Class C5-X Notional Amount A-6 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 25,000,000.00 Class C5-X A-6 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August October 1, 2005 First Distribution Date: September 26November 25, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C5-X A-6 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 25,000,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended, together with certain rights specified in the Pooling Agreement. The issue date of this Certificate is August 26October 27, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 9 Portion of the Class C2-X Notional Amount A-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 24,612,300.00 Class C2-X A-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August October 1, 2005 First Distribution Date: September 26November 25, 2005 Last Scheduled Distribution Date: September November 25, 2035 Class C2-X A-3 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 24,612,300.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August 26July 28, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT Series 2005-7 6 Portion of the Class C2-X Notional Amount A-3 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 4,252,334.00 Class C2-X A-3 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount Variable Cut-Off Date: August July 1, 2005 First Distribution Date: September 26August 25, 2005 Last Scheduled Distribution Date: September August 25, 2035 Class C2-X A-3 Principal Balance as of the Cut-Off Date: $0.00 Class C4,252,334.00 Cede & Co. Registered Owner WASHINGTON MUTUAL MORTGAGE PASS-X Notional Amount as of the Cut-Off Date: $14,369,296.00 THROUGH CERTIFICATE Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by

Trust. This Certificate represents ownership of a “regular interest” in a “real estate mortgage investment conduit,” as those terms are defined in Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as amended. The issue date of this Certificate is August April 26, 2005. Unless this Certificate is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange, or payment, and any Certificate issued is registered in the name of Cede & Co. or such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. WMALT The Class 1-CB-2 Certificates will provide credit support to another Class of Certificates, as described in the Pooling Agreement. Series 2005-7 3 Portion of the Class C1-X Notional Amount CB-2 Principal Balance as of the Cut-Off Date Evidenced by this Certificate: $14,369,296.00 2,049,000.00 Class C1-X CB-2 Certificate Interest Rate: 5.500%, applied to the Class C-X Notional Amount % Cut-Off Date: August April 1, 2005 First Distribution Date: September 26May 25, 2005 Last Scheduled Distribution Date: September May 25, 2035 Class C1-X CB-2 Principal Balance as of the Cut-Off Date: $0.00 Class C-X Notional Amount as of the Cut-Off Date: $14,369,296.00 2,049,000.00 Evidencing a beneficial interest in a pool of assets consisting of beneficial interests in another pool of assets consisting of beneficial interests in another pool of assets consisting of, among other things, conventional one- to four-family mortgage loans formed by