Stock index futures rose on Wednesday, taking a cue from gains in global markets, as the prospects of a rescue plan for heavily indebted Greece strengthened sentiment.

Investors awaited comments by Federal Reserve Chairman Ben Bernanke, who is expected to outline the central bank's strategy for withdrawing its extraordinary stimulus measures. His prepared testimony before the House Financial Services Committee will be released at 10:00 a.m., though the hearing has been postponed because of heavy snow.

European governments have agreed in principle to help Greece, German coalition sources told Reuters. However, a German government spokesman said a decision has not yet been reached.

The big story is the rescue plan that's being considered by Germany and the rest of its European partners to help ease some of the fear factors over Greece, said Peter Cardillo, chief market economist at Avalon Partners in New York.

If something is not done, then this could spread like wild fire. There are other weak countries within the euro zone that could be subject to speculation of default.

Earnings from Sprint Nextel Corp , which reported a narrower quarterly loss as revenue fell, sent its shares up slightly to $3.66 ahead of the opening bell.

S&P 500 futures rose 4.8 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 were up 46 points, and Nasdaq 100 futures gained 5.5 points.

In Europe, shares gained more than 1 percent, while in Asia, Japan's Nikkei average rose 0.3 percent.

On Tuesday, the Dow posted its largest one-day percentage gain in three months, boosted by reports of the aid plan for Greece.

China's top search engine Baidu Inc was up nearly 10 percent at $478.00 in premarket trade a day after it gave a strong outlook and said it would gain from Google Inc's high-profile threat to exit the country.

Shares in Walt Disney Co rose late Tuesday after the media and entertainment company reported better-than-expected earnings following a strong performance at its cable television division and cost cuts at its film studio.

(Editing by Padraic Cassidy)