Moody's Investors Service released a study, "Money Market Funds: US-Dollar Prime Funds' Credit and Liquidity Profiles Remained Resilient Throughout 2011," says, "The credit profiles of prime rated US-dollar-denominated money-market funds (MMFs) remained resilient over H2 2011, as funds adopted conservative management styles and significantly increased their investment in Aaa-rated government securities. Exposure to Aaa, Aa1 and Aa2-rated securities accounted for more than 59% of assets under management at the end of 2011, compared with 48% six months earlier. Prime funds drastically reduced their exposures to European banks. Overnight liquidity of this segment remains high: 38% on average in H2 2011 compared to 32% during H1 2011. Liquidity has increased in light of the ongoing market anxiety surrounding euro area debt crisis. generally -- and French banks in particular -- both in terms of aggregate exposures and duration, down to US$185 billion as of December 2011 from US$425 billion in January 2011. During Q4 2011, funds reduced their sensitivity to market risk, and maintained on average a stressed NAV level above 0.995." See also, "Money Market Funds: Euro Prime Funds Maintained Stable Credit and Liquidity Profiles Throughout 2011" and "Money Market Funds: Sterling Prime Funds Reduced Sensitivity to Market Risk in 2011."