Exhibit 13(b)

EX-99-906CERT

Certification pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

I, Ellen M. Needham, President and I, Bruce S. Rosenberg, Treasurer of the State Street Institutional Investment Trust (the “Trust”), each certify, to the best of my knowledge and belief, that:

1. This Form N-CSR filing of the Trust for the period ended June 30, 2019 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Trust.

By:	/s/ Ellen M. Needham
	Ellen M. Needham
	President (Principal Executive Officer) of the State Street Institutional Investment Trust
Date:	September 5, 2019
By:	/s/ Bruce S. Rosenberg
	Bruce S. Rosenberg
	Treasurer (Principal Financial and Accounting Officer) of the State Street Institutional Investment Trust
Date:	September 5, 2019