State Street's $29 million prime money market ETF trades with a floating NAV
State Street Institutional Investment Trust filed a Form 485BPOS on September 9, 2026 covering State Street Prime Money Market ETF MMK, which held $29.03 million as of September 8.
Key takeaways
The State Street Prime Money Market ETF MMK is a Rule 2a-7 prime money market fund that trades on the New York Stock Exchange, charges 0.18%, and does not hold a stable $1.00 share price. It began operations on February 10, five days after the trust brought the series effective. As of Tuesday, September 8, it held $29.03 million. State Street Institutional Investment Trust filed a post-effective amendment covering the fund on Wednesday.
The fund seeks to maximize current income, consistent with preserving capital and liquidity. Share price and net asset value are expected to fluctuate. It pays monthly: the latest distribution was $0.30958 a share, going ex-dividend on September 1 and paying on September 4.
The iShares Prime Money Market ETF PMMF, a prime money market fund that launched on February 4, 2025 and charges 0.20%, held $736 million as of Wednesday.
ETFs in this story
Frequently asked questions
Does this ETF hold a stable $1.00 share price?
No: it's a prime money market fund with a floating NAV, and both its share price and net asset value are expected to fluctuate.
What does it cost?
It charges 0.18%, versus 0.20% for the iShares Prime Money Market ETF.
Does it pay income?
Yes, monthly; the latest distribution was $0.30958 a share.
How does its size compare with the competing prime money market ETF?
It held $29.03 million, while the iShares fund held $736 million.
