One of few sectors of the mutual fund world to enjoy inflows in the past year have been money market funds, which have grown to comprise more than 40 per cent of mutual fund assets, or close to $4,000bn (£2,706bn, €3,018bn) under management.

As stock markets fell and concerns rose about risk levels in all asset classes, investors fled to safety and liquidity, stashing their money in bank deposits and in money market funds. The funds had a reputation for being as safe as bank deposits, although they had no federal guarantee.