Money market mutual funds that put cash into investments tied to the mortgage crisis and subprime debt saw huge gains last year, growing by more than 30% to $3 trillion, according to the South Florida Sun-Sentinel.

The agencies that rate the creditworthiness of top investments didn’t lower the ratings quickly enough to alert fund managers to the impending debt crisis, so many funds weren’t aware an investment was undervalued, Don Cassidy, president and founder of the nonprofit Retirement Investing Institute told the newspaper.

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