The world's biggest asset managers are lobbying for a last-minute reprieve from a European Union (EU) policy that could throw about 80 billion euros (US$94 billion) of money funds into turmoil.

BlackRock Inc., JPMorgan Chase & Co., and Goldman Sachs Group Inc. are among giants hoping to persuade EU authorities to preserve a key feature that investors have come to expect: the fixed share price. Public statements by regulators so far suggest that new rules that start on Jan. 21 will eliminate the ability of such funds to maintain the stable value, eroding the main appeal of such products.

Corporate treasurers around the world rely on money funds to park their cash with the assurance they'll be able to take out every dollar—or euro—when they need funds for payroll or investments. The new rules leave investors with even fewer safe places to stash their money, as many banks are reluctant to accept large cash balances, while deposit rates in the region are expected to stay below zero for at least another year. Floating-rate funds aren't a great alternative, especially for treasurers, because it would create tax and accounting headaches.