S&P 500 stock index futures rose at the start of electronic trading on Sunday after media reports detailed the U.S. Treasury's three-pronged bid to cleanse the financial system of toxic assets clogging banks' balance sheets.

The latest plan is aimed at banks and insurance companies given their large holdings of mortgages and other hard-to-price assets. The S&P financial index <.GSPF> has fallen 61 percent since the collapse of Lehman Brothers in September 2008.

S&P 500 futures rose 4.1 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract.