Fitch Ratings published "Money Fund Liquidity: Regulation Versus Risk Aversion". It says, "Since the U.S. credit crisis, the 10 largest U.S. prime money market funds (MMF) have significantly increased their allocations to liquid assets. At the end of 2006, liquid assets accounted for roughly 20% of total MMF assets.... As of end-September 2012, liquid assets represented about 45% of MMF assets. A meaningful portion of this increase is attributable to SEC rule changes implemented in 2010, which among other restrictions place a 30% floor on the level of liquid assets available in one week or less.... Additionally, the sizable liquidity buffer that funds are holding beyond these new regulatory minimums also reflects ongoing MMF risk aversion. Once market volatility eases, Fitch expects funds will, in turn, seek to reduce these buffers to take advantage of relatively higher-yielding, longer-duration investment opportunities. Financial market regulators have been focusing on MMF liquidity, given the importance of liquid assets in enabling money funds to weather periods of market volatility, to meet investor redemption requests, and to provide confidence in the sector as a whole. In particular, some SEC commissioners have called for further research on the extent to which 2010 Rule 2a-7 amendments have enhanced fund liquidity since their formal proposal in July 2009 and subsequent approval in February 2010."