Wall Street equity futures were lower on Tuesday as a last-minute congressional deal to raise the U.S. debt ceiling failed to assuage investor concerns that a credit downgrade could be avoided.

Concerns about the nation's fiscal situation have pressured equities recently, with the S&P falling for a sixth straight day on Monday, a decline that followed its worst week in a year last week.

While the congressional deal, which includes spending cuts of $2.4 trillion over 10 years, was seen as averting an unprecedented default, many investors fear it doesn't go far enough to satisfy rating agencies. A downgrade is expected to increase Treasury rates, raising the nation's borrowing costs.

The Senate is due to vote on the deal at noon (1600 GMT) after passing the Republican-led House of Representatives on Monday.

Overseas debt issues also returned to the forefront after French bank BNP Paribas unveiled a $768.3 million writedown linked to Greece's woes. Europe's FTSEurofirst 300 <.FTEU3> index of top shares fell 0.8 percent.

S&P 500 futures fell 4.8 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 30 points and Nasdaq 100 futures slid 9 points.

Companies due to report results on Tuesday include Pfizer
, CBS Corp , Duke Energy Corp , Marathon Oil Corp , Molson Coors Brewing and Tenet Healthcare . Economic indicators include July auto sales and personal income and consumption data for June.

Pfizer, a Dow component, is seen reporting lower earnings as competition from generic copies of its Lipitor cholesterol fighter hurt results. However, investors are expected to focus on what the pharmaceutical giant plans to do after Lipitor faces U.S. generics in November.

MetroPCS Communications Inc
posted quarterly profit Tuesday that fell short of analysts' estimates as it added fewer customers than expected.

Overseas, Toyota Motor Corp <7203.T> raised its full-year profit outlook, though to a level that was still below expectations, warning the stronger yen was hobbling it in the battle against South Korean rivals as it races to restore quake-hit production.

A senior executive at Sony Corp <6758.T> said the company would pull together plans this month to restructure its loss-making television unit.

U.S. stocks fell on Monday, with the S&P down for a sixth straight day, though the market pared losses late in the day.

( Editing by W Simon )