NEW YORK — Total U.S. money market mutual fund assets fell $9.66 billion to $2.612 trillion for the week that ended Wednesday, according to the Investment Company Institute.

Assets in the nation's retail money market mutual funds fell $1.54 billion to $918.93 billion, the Washington-based mutual fund trade group said Thursday. Assets of taxable money market funds in the retail category fell $720 million to $726.24 billion. Tax-exempt retail fund assets fell $830 million to $192.70 billion.

Assets in institutional money market funds fell $8.11 billion to $1.693 trillion. Among institutional funds, taxable money market fund assets fell $7.03 billion to $1.622 trillion. Assets of tax-exempt funds fell $1.09 billion to $70.95 billion.

The 7-day average yield on money market mutual funds was unchanged at 0.01 percent from the previous week, according to Money Fund Report, a service of iMoneyNet Inc. in Westborough, Mass. The 7-day compounded yield was flat at 0.01 percent. The 30-day yield and the 30-day compounded yield were both unchanged at 0.01 percent, Money Fund Report said Wednesday.

The online service said its survey of 100 leading commercial banks, savings and loan associations and savings banks in the nation's 10 largest markets showed the annual percentage yield available on money market accounts were unchanged from the week before at 0.11 percent.

The North Palm Beach, Fla.-based unit of Bankrate Inc. said Wednesday that the annual percentage yield available on interest-bearing checking accounts was unchanged from the week before at 0.05 percent. said the annual percentage yield on six-month certificates of deposit was flat at 0.15 percent. Rates were also flat at 0.24 percent on one-year CDs, 0.37 percent on two-year CDs and 0.77 percent on five-year CDs.