Stock index futures pointed to a higher open on Wall Street on Wednesday, with futures for the S&P 500 up 0.23 percent, Dow Jones futures up 0.32 percent and Nasdaq 100 futures up 0.77 percent at 0907 GMT.

Blockbuster sales of the iPhone and strong Asian business again helped Apple Inc crush Wall Street's expectations, driving its shares up more than 7 percent to a record high and boosting Asian stocks. Apple shares traded in Frankfurt were up 4 percent.

Yahoo plugged some of the holes that were weakening its Internet search business in the second quarter, but revealed new challenges that hurt its display advertising business.

U.S. cleaning products giant Ecolab Inc is expected to buy chemicals firm Nalco Holding Co and a deal could be announced as early as Wednesday morning, a source familiar with the situation told Reuters. Wall Street Journal had earlier reported that the Ecolab-Nalco deal could be valued at about $5 billion.

Wireless telecom firm T-Mobile USA said it will begin offering unlimited data service plans, in a move aimed at wooing customers of bigger rivals Verizon Wireless and AT&T Inc which had stopped offering such plans.

Altera Corp forecast third-quarter revenue well above estimates as the programmable chipmaker saw continuing demand from telecom operators ramping up their networks.

A top U.S. Federal Reserve official said on Thursday the U.S. economy should grow at a modest pace for the next several years, but issued a harsh criticism of the U.S. central bank's just-concluded bond buying program.

Investors awaited a raft of earnings on Wednesday, from companies such as Intel Corp , United Technologies Corp, American Express Co, eBay Inc , Johnson Controls Inc and Abbott Laboratories.

On the macro side, U.S. home sales data is due at 1400 GMT.

U.S. stocks recorded their best day since March on Tuesday after strong corporate results and renewed hope for an agreement in Washington on thorny budget issues boosted investor confidence.

The Dow Jones industrial average <.DJI> was up 202.11 points, or 1.63 percent, at 12,587.27. The Standard & Poor's 500 Index <.SPX> was up 21.27 points, or 1.63 percent, at 1,326.71. The Nasdaq Composite Index <.IXIC> was up 61.41 points, or 2.22 percent, at 2,826.52.

(Reporting by Blaise Robinson; Editing by Jon Loades-Carter)