NEW YORK — Total U.S. money market mutual fund assets rose $7.66 billion to $2.594 trillion for the week that ended Wednesday, according to the Investment Company Institute.

Assets of the nation's retail money market mutual funds rose $4.74 billion to $923.83 billion, the Washington-based mutual fund trade group said Thursday. Assets of taxable money market funds in the retail category rose $5.42 billion to $732.56 billion. Tax-exempt retail fund assets fell $670 million to $191.26 billion.

Meanwhile assets of institutional money market funds rose $2.92 billion to $1.671 trillion. Among institutional funds, taxable money market fund assets fell $3.42 billion to $1.6 trillion. Assets of tax-exempt funds fell $510 million to $70.45 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 average maturity of portfolios held by money market mutual funds rose to 49 days from 48 days.

The online service Bankrate.com 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.

Bankrate.com said the annual percentage yield on six-month certificates of deposit was flat at 0.15 percent. It was also flat at 0.24 percent on one-year CDs, flat at 0.37 percent on two-year CDs and flat at 0.78 percent on five-year CDs.