Common use of PROSPECTUS SUPPLEMENT SUMMARY Clause in Contracts

PROSPECTUS SUPPLEMENT SUMMARY. This summary highlights some of the information in this prospectus supplement and may not contain all of the information that is important to you. For a more complete understanding of this offering, we encourage you to read this entire prospectus supplement and the accompanying prospectus and the documents that are referenced in this prospectus supplement and the accompanying prospectus, together with any accompanying supplements. In this prospectus supplement and the accompanying prospectus, unless the context otherwise requires, the “Company,” “Hercules,” “HTGC,” “we,” “us” and “our” refer to Hercules Capital, Inc. and its wholly-owned subsidiaries and its affiliated securitization trusts. Our Company We are a specialty finance company focused on providing senior secured loans to high-growth, innovative venture capital-backed companies in a variety of technology, life sciences, and sustainable and renewable technology industries. Our investment objective is to maximize our portfolio’s total return by generating current income from our debt investments and capital appreciation from our warrant and equity-related investments. We are an internally-managed, non-diversified, closed-end investment company that has elected to be regulated as a business development company under the 1940 Act. Effective January 1, 2006, we elected to be treated for tax purposes as a RIC under the Internal Revenue Code of 1986, as amended, or the Code. As of December 31, 2018, our total assets were approximately $1.9 billion, of which our investments comprised $1.9 billion at fair value and $2.0 billion at cost. Since inception through December 31, 2018, we have made debt and equity commitments of more than $8.5 billion to our portfolio companies. We also make investments in qualifying small businesses through Hercules Technology III, L.P., or HT III, which is our wholly owned SBIC. HT III holds approximately $307.5 million in assets which accounted for approximately 14.3% of our total assets, prior to consolidation at December 31, 2018. At December 31, 2018, we have issued $149.0 million in SBA-guaranteed debentures in our SBIC subsidiary. See “Regulation—Small Business Administration Regulations” in the accompanying prospectus for additional information regarding our SBIC subsidiary. As of December 31, 2018, our investment professionals, including Xxxxxx X. Xxxxxxxxx, ourco-founder, Chairman, President and Chief Executive Officer, are currently comprised of 36 professionals who have, on average, more than 10 years of experience in venture capital, structured finance, commercial lending or acquisition finance with the types of technology-related companies that we are targeting. We believe that we can leverage the experience and relationships of our management team to successfully identify attractive investment opportunities, underwrite prospective portfolio companies and structure customized financing solutions. Organizational Chart The following chart summarizes our organizational structure as of February 25, 2019. This chart is provided for illustrative purposes only. Our Market Opportunity We believe that technology-related companies compete in one of the largest and most rapidly growing sectors of the U.S. economy and that continued growth is supported by ongoing innovation and performance improvements in technology products as well as the adoption of technology across virtually all industries in response to competitive pressures. We believe that an attractive market opportunity exists for a specialty finance company focused primarily on investments in structured debt with warrants in technology-related companies for the following reasons: • technology-related companies have generally been underserved by traditional lending sources; • unfulfilled demand exists for structured debt financing to technology-related companies due to the complexity of evaluating risk in these investments; and • structured debt with warrants products are less dilutive and complement equity financing from venture capital and private equity funds.

PROSPECTUS SUPPLEMENT SUMMARY. This summary highlights some of the information in this prospectus supplement and may not contain all of the information that is important to you. For a more complete understanding of this offering, we encourage you to read this entire prospectus supplement and the accompanying prospectus and the documents that are referenced in this prospectus supplement and the accompanying prospectus, together with any accompanying supplements. In this prospectus supplement and the accompanying prospectus, unless the context otherwise requires, the “Company,” “Hercules,” “HTGC,” “we,” “us” and “our” refer to Hercules Capital, Inc. and its wholly-owned subsidiaries and its affiliated securitization trusts. Our Company We are a specialty finance company focused on providing senior secured loans to high-growth, innovative venture capital-backed companies in a variety of technology, life sciences, sciences and sustainable and renewable technology industries. Our investment objective is to maximize our portfolio’s total return by generating current income from our debt investments and capital appreciation from our warrant and equity-related investments. We are an internally-managed, non-diversified, diversified closed-end investment company that has elected to be regulated as a business development company under the 1940 Act. Effective January 1, 2006, we elected to be treated for tax purposes as a RIC under the Internal Revenue Code of 1986, as amended, or the Code. As of December March 31, 2018, our total assets were approximately $1.9 1.6 billion, of which our investments comprised $1.9 1.5 billion at fair value and $2.0 1.6 billion at cost. Since inception through December March 31, 2018, we have made debt and equity commitments of more than $8.5 7.6 billion to our portfolio companies. We also make investments in qualifying small businesses through our two wholly-owned SBICs. Our SBIC subsidiaries, Hercules Technology II, L.P., or XX XX, and Hercules Technology III, L.P., or HT III, which is our wholly owned SBIC. HT III holds hold approximately $307.5 113.1 million and $285.8 million in assets which assets, respectively, and accounted for approximately 14.35.7% and 14.4% of our total assets, respectively, prior to consolidation at December March 31, 2018. At December March 31, 2018, we have issued $149.0 190.2 million in SBA-guaranteed debentures in our SBIC subsidiarysubsidiaries. See “Regulation—Small Business Administration Regulations” in the accompanying prospectus for additional information regarding our SBIC subsidiarysubsidiaries. As of December March 31, 2018, our investment professionals, including Xxxxxx X. Xxxxxxxxx, ourco-founder, Chairman, President and Chief Executive Officer, are currently comprised of 36 33 professionals who have, on average, more than 10 15 years of experience in venture capital, structured finance, commercial lending or acquisition finance with the types of technology-related companies that we are targeting. We believe that we can leverage the experience and relationships of our management team to successfully identify attractive investment opportunities, underwrite prospective portfolio companies and structure customized financing solutions. Organizational Chart The following chart summarizes our organizational structure as of February 25May 29, 20192018. This chart is provided for illustrative purposes only. Our Market Opportunity We believe that technology-related companies compete in one of the largest and most rapidly growing sectors of the U.S. economy and that continued growth is supported by ongoing innovation and performance improvements in technology products as well as the adoption of technology across virtually all industries in response to competitive pressures. We believe that an attractive market opportunity exists for a specialty finance company focused primarily on investments in structured debt with warrants in technology-related companies for the following reasons: • technology-related companies have generally been underserved by traditional lending sources; • unfulfilled demand exists for structured debt financing to technology-related companies due to the complexity of evaluating risk in these investments; and • structured debt with warrants products are less dilutive and complement equity financing from venture capital and private equity funds.

PROSPECTUS SUPPLEMENT SUMMARY. This summary highlights some of the information in this prospectus supplement and may not contain all of the information that is important to you. For a more complete understanding of this offering, we encourage you to read this entire prospectus supplement and the accompanying prospectus and the documents that are referenced in this prospectus supplement and the accompanying prospectus, together with any accompanying supplements. In this prospectus supplement and the accompanying prospectus, unless the context otherwise requires, the “Company,” “Hercules,” “HTGC,” “we,” “us” and “our” refer to Hercules Capital, Inc. and its wholly-owned subsidiaries and its affiliated securitization trusts. Our Company We are a specialty finance company focused on providing senior secured loans to high-growth, innovative venture capital-backed companies in a variety of technology, life sciences, and sustainable and renewable technology industries. Our investment objective is to maximize our portfolio’s total return by generating current income from our debt investments and capital appreciation from our warrant and equity-related investments. We are an internally-managed, non-diversified, closed-end investment company that has elected to be regulated as a business development company BDC under the 1940 Act. Effective January 1, 2006, we elected to be treated for tax purposes as a RIC under the Internal Revenue Code of 1986, as amended, or the Code. As of December March 31, 20182020, our total assets were approximately $1.9 2.4 billion, of which our investments comprised $1.9 2.3 billion at fair value and $2.0 2.5 billion at cost. Since inception through December March 31, 20182020, we have made debt and equity commitments of more than $8.5 10.0 billion to our portfolio companies. We also make investments in qualifying small businesses through Hercules Technology III, L.P., or HT III, which is our wholly owned SBIC. HT III holds approximately $307.5 193.3 million in tangible assets which accounted for approximately 14.38.1% of our total assets, prior to consolidation assets at December March 31, 20182020. At December March 31, 20182020, we have issued $149.0 110.3 million in SBA-guaranteed debentures in our SBIC subsidiarysubsidiary outstanding. See “Regulation—Small Business Administration Regulations” in the accompanying prospectus for additional information regarding our SBIC subsidiary. As of December 31June 30, 20182020, our investment professionals, including Xxxxxx X. Xxxxx Xxxxxxxxx, ourco-founder, Chairman, President our Chief Executive Officer and Chief Executive Investment Officer, are currently comprised of 36 44 professionals who have, on average, more than 10 years of experience in venture capital, structured finance, commercial lending or acquisition finance with the types of technology-related companies that we are targeting. We believe that we can leverage the experience and relationships of our management team to successfully identify attractive investment opportunities, underwrite prospective portfolio companies and structure customized financing solutions. Organizational Chart The following chart summarizes our organizational structure as of February 25June 30, 20192020. This chart is provided for illustrative purposes only. Our Market Opportunity We believe , and does not include subsidiaries that technology-related companies compete in one of the largest and most rapidly growing sectors of the U.S. economy and that continued growth is supported by ongoing innovation and performance improvements in technology products as well as the adoption of technology across virtually all industries in response to competitive pressures. We believe that an attractive market opportunity exists for a specialty finance company focused primarily on investments in structured debt with warrants in technology-related companies for the following reasons: • technology-related companies do not presently have generally been underserved by traditional lending sources; • unfulfilled demand exists for structured debt financing to technology-related companies due to the complexity of evaluating risk in these investments; and • structured debt with warrants products are less dilutive and complement equity financing from venture capital and private equity fundsmaterial assets or operations.

PROSPECTUS SUPPLEMENT SUMMARY. This summary highlights some of contains basic information about us and the information in this prospectus supplement and may offering but does not contain all of the information that is important to youyour investment decision. For a more complete understanding of this offering, we encourage you to You should read this entire prospectus supplement and summary together with the accompanying prospectus and the documents that are referenced more detailed information contained elsewhere in this prospectus supplement and accompanying prospectus and in the statement of additional information, especially the information set forth under the heading “Risk Factors” beginning on page 39 of the accompanying prospectus, together with any accompanying supplements. In When used in this prospectus supplement and the accompanying prospectus, unless the context otherwise requiressupplement, the “Company,” “Hercules,” “HTGC,” terms “we,” “us,” and “our” refer to Hercules CapitalTortoise Energy Infrastructure Corporation, Inc. and its wholly-owned subsidiaries and its affiliated securitization trustsunless specified otherwise. Our The Company We are a specialty finance company focused on providing senior secured loans seek to high-growth, innovative venture capital-backed companies provide our stockholders with an efficient vehicle to invest in a variety portfolio of technology, life sciences, and sustainable and renewable technology industriespublicly traded MLPs in the energy infrastructure sector. Our investment objective is to maximize our portfolio’s seek a high level of total return by generating with an emphasis on current income from distributions paid to stockholders. For purposes of our debt investments and investment objective, total return includes capital appreciation from our warrant of, and equity-related investmentsall distributions received from, securities in which we invest regardless of the tax character of the distributions. We are an internally-managed, non-diversifieda nondiversified, closed-end management investment company that has elected to be regulated registered under the Investment Company Act of 1940, as amended (the “1940 Act”). We were organized as a business development company corporation on October 30, 2003, pursuant to a charter (the “Charter”) governed by the laws of the State of Maryland. Our fiscal year ends on November 30. We commenced operations in February 2004 following our initial public offering. Our common stock is listed on the NYSE under the 1940 Act. Effective January 1symbol “TYG.” As of May 31, 20062017, we elected had net assets of approximately $1,400.7 million attributable to be treated for tax purposes as a RIC under the Internal Revenue Code of 1986, as amended, or the Codeour common stock. As of December 31August 21, 20182017, we had outstanding $165.0 million of our total assets were approximately $1.9 billion, of which our investments comprised $1.9 billion at fair value Mandatory Redeemable Preferred Stock and $2.0 billion 412.5 million of our privately placed Senior Notes. We have established an unsecured credit facility with U.S. Bank N.A. serving as a lender and the lending syndicate agent on behalf of other lenders participating in the credit facility, which currently allows us to borrow up to $130.0 million. Outstanding balances under the credit facility generally accrue interest at costa variable annual rate equal to the one-month LIBOR rate plus 1.20%, with a tiered non-use fee on an unused balance of the credit facility. Since inception Non-use fees accrue at a rate of 0.25% when the outstanding balance on the facility is below $65 million and 0.15% when the outstanding balance on the facility is at least $65 million, but below $91 million. The outstanding balance is not subject to the non-use fee when the amount outstanding is at least $91 million. As of August 21, 2017, the effective rate was 2.44%. The credit facility remains in effect through December 31June 12, 20182019. We may draw on the facility from time to time to fund investments in accordance with our investment policies and for general corporate purposes. As of August 21, 2017, we had outstanding $45.8 million under the credit facility. We have made debt and equity commitments also established an unsecured credit facility with Scotia Bank, N.A. which currently allows us to borrow up to $90 million. Outstanding balances under the credit facility generally accrue interest at a variable annual rate equal to the one-month LIBOR rate plus 1.20%, with a fee of more 0.15% on any unused balance of the credit facility if the amount borrowed under the facility is less than $8.5 billion to our portfolio companies63 million. We also make investments As of August 21, 2017, the effective rate was 2.44%. The credit facility remains in qualifying small businesses effect through Hercules Technology III, L.P., or HT III, which is our wholly owned SBIC. HT III holds approximately $307.5 million in assets which accounted for approximately 14.3% of our total assets, prior to consolidation at December 31June 22, 2018. At December We may draw on the facility from time to time to fund investments in accordance with our investment policies and for general corporate purposes. As of August 21, 2017, we had outstanding $63 million under the credit facility. Investment Adviser Tortoise Capital Advisors, L.L.C., a registered investment adviser specializing in essential assets investing (the “Adviser”), serves as our investment adviser. Essential assets are those that are indispensable and necessary to the functioning of our economy and our society as a whole, such as education, healthcare, infrastructure and energy. As of July 31, 20182017, we have issued the Adviser managed assets of approximately $149.0 million in SBA16.6 billion, including the assets of publicly traded closed-guaranteed debentures in our SBIC subsidiaryend management investment companies, open-end funds, private funds and other accounts. The Adviser’s investment committee is comprised of eight portfolio managers. See “Regulation—Small Business Administration RegulationsManagement of the Company” in the accompanying prospectus. The principal business address of the Adviser is 00000 Xxx Xxxxxx, Xxxxx 000, Xxxxxxx, Xxxxxx 00000. The Offering Common stock offered Up to $120,000,000 Use of proceeds We intend to use the net proceeds of this offering primarily to repay short-term debt outstanding under our credit facility and to invest in energy infrastructure companies in accordance with our investment objective and policies or for working capital purposes. See “Use of Proceeds.” Risk factors See the section titled “Risk Factors” and other information included in the accompanying prospectus for additional information regarding our SBIC subsidiary. As a discussion of December 31, 2018, our investment professionals, including Xxxxxx X. Xxxxxxxxx, ourco-founder, Chairman, President and Chief Executive Officer, are currently comprised of 36 professionals who have, on average, more than 10 years of experience factors you should carefully consider before deciding to invest in venture capital, structured finance, commercial lending or acquisition finance with the types of technology-related companies that we are targeting. We believe that we can leverage the experience and relationships shares of our management team common stock. NYSE symbol “TYG” Stockholder transaction expenses: Sales load (as a percentage of offering price) Up to successfully identify attractive investment opportunities, underwrite prospective portfolio companies and structure customized financing solutions. Organizational Chart The following chart summarizes our organizational structure 2.00% Offering expenses borne by us (as a percentage of February 25, 2019. This chart is provided for illustrative purposes only. Our Market Opportunity We believe that technology-related companies compete in one of the largest and most rapidly growing sectors of the U.S. economy and that continued growth is supported by ongoing innovation and performance improvements in technology products as well as the adoption of technology across virtually all industries in response to competitive pressures. We believe that an attractive market opportunity exists for a specialty finance company focused primarily on investments in structured debt with warrants in technology-related companies for the following reasons: • technology-related companies have generally been underserved by traditional lending sources; • unfulfilled demand exists for structured debt financing to technology-related companies due to the complexity of evaluating risk in these investments; and • structured debt with warrants products are less dilutive and complement equity financing from venture capital and private equity funds.offering price) 0.21% Dividend reinvestment plan fees(1) None