Money market mutual fund assets hit a record $655.96 billion in the week that ended March 22, the Investment Company Institute reported.

The new total, a 0.8% gain in the week, topped the previous high of $653.32 billion, set Jan. 31.

Money market assets have been rising steadily over the past year. The gains owe much to higher yields on the investments, but they also reflect "the continued expansion of mutual fund investing generally," said a spokesman for the institute.

The increase was concentrated in taxable money market funds. Some $5.6 billion flowed into these funds, versus a $477 million outflow from tax-exempt funds.

On the retail side, money market fund assets rose 0.5%, to $462.44 billion. That includes $366.6 billion in taxable funds, up $2.43 billion, and $95.84 billion in tax-exempt funds, down $180.4 million.

Institutional money market assets climbed 1.5%, to $193.52 billion. Taxable funds held $169.82 billion of the total, a $3.16 billion rise, while tax-exempt funds held $23.7 billion, down $296.5 million. - Debra Cope

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