Every U.S. treasurer who parks corporate cash in money funds should already be well aware of the regulatory changes taking effect this Friday. Prime money market mutual funds will have to shift to a floating net asset value (NAV), and the funds' boards will have to consider implementing redemption fees or gates if liquidity falls below specific levels.

"This is a big change," says John Donohue, head of global liquidity for JPMorgan Chase. "It's one of the biggest changes that's ever happened in this space."

Donohue downplays the effects of the floating NAV on corporate investors. "While the NAV is floating, the funds will still be subject to the same investment guidelines they always were subject to," he says. "So if the NAV does float, it's going to be with very, very low volatility. These funds have always floated, they've just floated in such a narrow band that they've always rounded up or down to par."