Stock index futures fell on Wednesday, a day after the Nasdaq stock index <.IXIC> clinched a 10-day winning streak, as investors braced for another round of quarterly results from bellwethers including Morgan Stanley and Boeing Co .

Investors will be closely watching as Federal Reserve Chairman Ben Bernanke continues his congressional testimony on the economic outlook and monetary policy, now before the Senate Banking Committee, at 10 a.m. EST. On Tuesday, Bernanke was cautious about the economic recovery.

Other companies reporting quarterly scorecards include Qualcomm , Altria and Wells Fargo .

S&P 500 futures fell 4.4 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 32 points and Nasdaq 100 futures dropped 3.75 points.

Apple Inc posted on Tuesday quarterly profits that beat forecasts, helped by robust sales of Mac computers and iPhones and higher-than-expected gross margins, sending its shares up 3.6 percent in premarket trading. A surge in Apple shares could help the Nasdaq extend its current 10-day winning streak, its longest in 12 years.

Yahoo Inc's third-quarter forecasts fell short of Wall Street expectations late on Tuesday as the Internet company announced plans to step up spending despite persistent weakness in the advertising market.

Crude futures fell more than 1 percent to less than $65 per barrel after data showing an unexpected rise in U.S. crude stocks suggested demand in the world's top energy consumer was still weak.

U.S. shares gained ground on Tuesday as strong results from Caterpillar Inc eclipsed some uneasiness about the company's outlook for the current quarter, but the gains were limited as some investors paused following the recent earnings-fueled run-up.

(Reporting by Rodrigo Campos; Editing by Theodore d'Afflisio)