Money marketing fund may be breaking the buck?

Money market funds are usually seen as the safest investment form of all mutual funded vehicles.Because for years most money market accounts usually invest t-bills which are government notes backed by united states government which means you have the best chance of getting your money back. But ,Lately a lot money market accounts have invested in S.I.V accounts which are structured investment vehicles which has a real estate foundation and I think everyone is aware of the sub prime lending crisis. Like the stocks but differently ,money market funds a $1 a share and with this volatile investments called S.I.V. money market funds might strike below the $1 which might be the first time in history. Remember over 3 trillion dollars of U.S dollars are in money market funds imagine that impact on the economy. I am not say money marketing accounts are bad I am just saying make sure it is S.I.V. free meaning look for high yield money market accounts and make sure it doesn't use S.I.V.s.