WASHINGTON AP – Federal regulators on Wednesday proposed tightened rules for money-market mutual funds that would require them to hold some assets that could be easily converted to cash and to invest only in the highest quality securities.

The Securities and Exchange Commission proposal came after a $60 billion money fund “broke the buck,” exposing investors to losses that could ultimately reach about 8 cents on the dollar. The value of the Primary Reserve Fund’s assets in September fell to 97 cents per investor dollar – below the dollar-for-dollar level needed for full repayment.