U.S. stock index futures pointed to a lower open on Wednesday after disappointing quarterly banking results dented recent optimism about the financial sector's recovery.

A third-consecutive quarterly loss at Morgan Stanley and rising credit losses at Wells Fargo & Co pushed those shares lower in premarket trading by 5 percent.

There's fear of more losses across the financial spectrum. Regardless of what they did in the second quarter, the thought is there's more bad (news) to come, said Jim Paulsen, chief investment officer at Wells Capital Management in Minneapolis.

You also have this coming in after a pretty good run, and the market is vulnerable because it is so extended.

Also on Wednesday Federal Reserve Chairman Ben Bernanke begins a second round of testimony in Congress, with investors looking for clues on how the Fed plans to balance its actions to help the economy recover while avoiding weakening the U.S. dollar further.

Bernanke pointed out the fragility of the recovery and led a lot of investors to reconsider whether a policy of low interest rates is what the stock market needs to continue its recovery, or will lead to further problems down the road, said Rick Meckler, president of LibertyView Capital Management in New York.

Bernanke's testimony before the Senate Banking Committee begins at 10 a.m. EST.

S&P 500 futures fell 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 75 points and Nasdaq 100 futures dropped 5 points.

Regional bank KeyCorp posted a wider-than-expected loss hurt by bad loans, and its shares fell more than 5 percent in premarket trade.

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 more than 4 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.

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.

(Editing by Padraic Cassidy)