NEW YORK (AP) — Total U.S. money market mutual fund assets rose $18.56 billion to $2.551 trillion for the week that ended Wednesday, the Investment Company Institute said Thursday.

Assets of the nation’s retail money market mutual funds fell $1.56 billion to $886.34 billion, the Washington-based mutual fund trade group said. Assets of taxable money market funds in the retail category fell $2.39 billion to $698.15 billion. Tax-exempt retail fund assets rose $830 million to $188.19 billion.