U.S. stock index futures rose on Wednesday as solid earnings from technology giant Apple along with financials Morgan Stanley and Wells Fargo eased growth concerns.

Apple Inc gained 3.4 percent to $260.51 in premarket trade after an unusually upbeat revenue forecast calmed concerns that iPhone 4 antenna problems would dampen sales.

Apple was a bright spot after a string of disappointing revenue results, including ones from International Business Machines Corp and chipmaker Texas Instruments Inc

Investors closely watched top-line numbers for signs of growth in the economy as recent data has signaled a slowdown.

Apple broke the streak of companies who beat on earnings but missed on revenues, and maybe you can gauge some optimism from investors that maybe there is nothing structurally wrong with the economy that wouldn't allow companies to grow if the products are right, said Rick Meckler, president of investment firm LibertyView Capital Management in New York.

Apple offered some hope that it is not an all-or-nothing situation, that growth is possible.

S&P 500 futures gained 4.6 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. Dow Jones industrial average futures added 29 points, and Nasdaq 100 futures advanced 15.5 points.

Futures extended gains after Morgan Stanley and Wells Fargo & Co gained posted quarterly results.

Morgan Stanley advanced 2.7 percent to $25.90, while Wells Fargo climbed 3.2 percent to $26.75 premarket.

Diversified U.S. manufacturer United Technologies Corp reported a 13.7 percent rise in profit and raised its full-year forecast, saying demand and margins improved.

Fellow Dow component Coca-Cola Co gained 1.4 percent to $54 after the soft-drink maker reported higher quarterly profit on Wednesday, helped by increased revenue and sales volume.

BP Plc denied a report its heavily criticized chief executive would soon leave as the company lined up $7 billion in asset sales to Apache Corp to help cover the cost of the massive Gulf of Mexico oil spill. Separately, Apache said it will sell 21 million common shares.

BP's U.S.-traded shares gained 4.1 percent to $36.65, while Apache slipped 1.8 percent to $86.69.

U.S. Federal Reserve Chairman Ben Bernanke, in testimony before Congress at 2 p.m. EDT <1800 GMT>, may provide a fresh outlook on the health of the world's biggest economy as well as policy signals from the central bank.

European stocks climbed for the first time in a week on Wednesday in a broad rally, with investors scooping up battered banking shares on hopes the sector's stress test results will be reassuring.

Asian stocks rose on Apple's strong earnings and optimism that China may roll back policy-tightening measures later this year, while the euro firmed ahead of the euro zone bank stress test results late in the week.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)