The SEC's changes to money market fund regulations aim to make the funds less vulnerable to a rush of withdrawals in times of financial stress. But the new rules will also make money funds, especially prime funds, a less hospitable destination for short-term corporate cash.

For corporate treasurers, the regulatory changes pose challenges ranging from the uncertainty created by the possible imposition of liquidity fees and gates to the effort and cost treasuries will have to expend to prepare for the changes.

The SEC voted in July to allow money funds to use liquidity fees and gates to limit investor withdrawals in times of stress. The agency also mandated that municipal funds and institutional prime funds—those that invest in corporate debt—use a floating net asset value (NAV) instead of the stable, $1-a-share pricing that is currently the standard. Money funds have two years to comply with the changes.