In a global financial environment dominated by negative interestrates and central banks signaling even more accommodative policies,the U.S. money-market industry is thriving.

Normally seen as a place to park cash during times ofuncertainty, taxable funds have seen roughly $136 billion ofinflows this year, even with U.S. equity markets surging and bondsposting positive returns, Investment Company Institute data show.Overall assets have swelled to more than $3 trillion, the highestlevel since the financial crisis.

Demand is being aided in part by attractive U.S. short-termyields relative to bank deposits—helped by three years of FederalReserve interest-rate hikes, an inverted yield curve, and volatility infinancial markets. Total assets in government money funds are at arecord high, and investments in prime funds are the most sinceSeptember 2016, before industry reforms went into effect.