U.S. stock index futures climbed on Wednesday after solid earnings and outlooks from major technology companies renewed optimism over the economic recovery.

Intel Corp jumped 6.3 percent to $21.11 in premarket trade after forecasting quarterly revenues well above Wall Street's estimates, easing fears the world's largest chipmaker is struggling as personal computer sales growth wanes.

Yahoo Inc advanced 4.8 percent to $16.90 after the company said an important partnership with Microsoft Corp is taking longer than expected to pay off, but the company posted quarterly earnings that topped Wall Street targets.

But IBM slipped 1.2 percent to $163.49 after reporting a decline in signings of new business at its global services division during the first quarter, even as its profit and revenue came in ahead of analysts' projections.

Other companies scheduled to report quarterly results on Wednesday include Apple Inc , American Express Co , AT&T Inc and Freeport-McMoRan Copper & Gold .

Apple is expected to report quarterly results on Wednesday, tempered by caution over how supply constraints will squeeze margins and restrain iPhone and iPad sales.

S&P 500 futures added 18 points and were above 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 gained 136 points and Nasdaq 100 futures rose 31 points.

Economic indicators include March existing-home sales at 10 a.m..

On the M&A front, U.S. power company AES Corp said it would buy smaller rival DPL Inc for $3.5 billion in cash to expand in the Midwest by adding 500,000 retail customers in West Central Ohio.

European shares rose sharply on Wednesday, tracking gains on Wall Street and in Asia, after strong sales at Intel and other U.S. firms boosted optimism for European companies' results. <.EU>

Asian stocks rose as strong results from Intel prompted a rally in tech shares, while renewed strength in metals prices boosted materials companies and also lifted the commodity-linked Australian dollar.

Encouraging results from healthcare and materials companies lifted U.S. stocks on Tuesday, but weak earnings from Goldman Sachs limited gains in a market skeptical of the growth outlook.

(Reporting by Chuck Mikolajczak; Editing by Kenneth Barry)

Apple inc. Intel