Joint Filing Agreement, dated September 24, 2013 PURSUANT TO RULE 13d-1(k)

EXHIBIT 4

Joint Filing Agreement, dated September 24, 2013

PURSUANT TO RULE 13d-1(k)

The undersigned acknowledge and agree that the foregoing statement on Schedule 13D is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13D may be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows that such information is inaccurate.

Dated: September 24, 2013.

	CASTLERIGG MASTER INVESTMENTS LTD.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	CASTLERIGG INTERNATIONAL LIMITED
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer

38

	CASTLERIGG INTERNATIONAL HOLDINGS LIMITED
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	CASTLERIGG OFFSHORE HOLDINGS, LTD.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	CASTLERIGG MERGER ARBITRAGE AND EQUITY EVENT FUND, LTD.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	CASTLERIGG MERGER ARBITRAGE AND EQUITY EVENT INTERMEDIATE FUND, L.P.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer

39

	CASTLERIGG MERGER ARBITRAGE AND EQUITY EVENT MASTER FUND, LTD.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	CASTLERIGG GLOBAL EQUITY SPECIAL EVENT FUND, LTD.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	CASTLERIGG GLOBAL EQUITY SPECIAL EVENT INTERMEDIATE FUND, LTD.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	CASTLERIGG GLOBAL EQUITY SPECIAL EVENT MASTER FUND, LTD.
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer

40

	CASTLERIGG UCITS FUNDS PLC, an umbrella fund with segregated liability between sub-funds acting for and on behalf of Castlerigg Merger Arbitrage UCITS Fund
	By:	Xxxxxxx Investment Services, L.L.C., as Investment Manager
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	PULTENEY STREET PARTNERS, LP
	By:	Xxxxxxx Asset Management Corp., as Investment Manager
	By:	/s/ Xxxx XxXxxxx
	Name:	Xxxx XxXxxxx
	Title:	Managing Member
	XXXXXXX ASSET MANAGEMENT CORP.
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Chief Executive Officer
	XXXXXXX INVESTMENT SERVICES, L.L.C.
	By:	/s/ Xxxxxx X. Xxxxxxx
	Name:	Xxxxxx X. Xxxxxxx
	Title:	Managing Member
	/s/ Xxxxxx X. Xxxxxxx
	Xxxxxx X. Xxxxxxx