CYS Investments 10-Q 2013 Q3 Quarterly report

Exhibit 32.1

Certification Pursuant To

18 U.S.C. Section 1350,

as Adopted Pursuant to

Section 906 of The Sarbanes-Oxley Act of 2002

In connection with the Quarterly Report of CYS Investments, Inc. (the “Company”) on Form 10-Q for the period ended September 30, 2013 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Kevin E. Grant, Chairman of the Board and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: October 18, 2013

/s/    KEVIN E. GRANT        

Kevin E. Grant

Chairman of the Board

and Chief Executive Officer