Five years on from the start of the financial crisis, regulators on both sides of the Atlantic are still arguing with the fund management industry over the $4 trillion money market fund sector, leaving investors none the wiser on where to place their assets.

Money-market funds are funds that invest in cash, or cash-like assets such as short term government and corporate debt. They are supposed to be one of the least risky investments and aim never to lose money. Many investors have treated this as an implicit guarantee that the funds will maintain a constant net asset value.