FFQ9 is the 30-day August Federal Funds futures contract. It's priced as a simple average of Daily Effective Federal Funds Rate (hereafter "EFFR") for each day of the month. That rate is published in arrears (i.e. what's published today is yesterday's rate) on a daily basis at 9:00am EST by the New York Fed. It's currently 2.13% (3bps over IOER).

IMPORTANT NOTE: There's an extremely large number of realistic possible outcomes, including those where IOER continues to drift lower. There are reasons relating to the plumbing of the money markets that make this unlikely, but it's a possibility. I'm only addressing the one which is most pressing: the market-implied probability of an emergency Fed ease.

EFFR has been trading anywhere from flat vs IOER to 5bps over for the better part of the last 6 months. When the Fed cut rates on July 31, EFFR went down by 26bps - from 2.40% to 2.14%. It stayed at 2.14% for the first two business days of the month, then went to 2.13%.