Assets in U.S. money market funds fell 0.45%, to $810.57 billion for the week ended March 28, according to the Investment Company Institute.
The decline was fueled by outflows from both retail and institutional portfolios.
Assets of the nation's 668 retail money market mutual funds fell by $1.77 billion during the week, to $567.14 billion. Taxable money market assets fell $1.1 billion, and tax-exempt portfolios lost $669 million.
Assets of the 292 institutional money funds fell by $2.64 billion, to $243.4 billion. Taxable portfolios fell $2.41 billion; tax-exempt funds, $221.8 million.