 "Wall St opens higher as GM, Boeing beat estimates")
Shares of General Motors rose 4 percent to $34.84, while Boeing rose 2 percent to $141.68, providing the biggest boost to the Dow.
Biogen rose 7.8 percent to $286.45 after it said it would cut 11 percent of its workforce and reported better-than-expected results. The stock gave the biggest boost to the S&P 500 and Nasdaq composite indexes.
"During the course of the third quarter, we actually saw consensus estimates drop for both revenue and earnings," said Eric Weigand, senior portfolio manager at the Private Client Reserve at U.S. Bank.
"You could make the point that there is a low hurdle for companies to exceed on these diminished expectations."
Of the S&P 500 companies that have reported results so far, 40 percent have exceeded revenue estimates. About 60 percent typically beat estimates in a quarter, according to Thomson Reuters data.
S&P 500 companies are expected to report a 3.9 percent decline in third-quarter profit and a 3.8 percent fall in revenue.
More From This Section
At 9:40 a.m. ET (1340 GMT), the Dow Jones industrial average was up 34.25 points, or 0.2 percent, at 17,251.36, the S&P 500 was up 2.75 points, or 0.14 percent, at 2,033.52 and the Nasdaq composite index was up 6.29 points, or 0.13 percent, at 4,887.26.
Eight of the 10 major S&P sectors rose, with the industrials sector's 0.5 percent rise leading the advancers.
Coca-Cola fell 1.2 percent to $41.79 after its revenue missed estimates.
American Express and eBay report after the close.
Adding to the upbeat mood on Wednesday were two large tech acquisitions.
Sandisk jumped 3.5 percent to $77.82 after it agreed to be bought by Western Digital in a $19 billion deal.
KLA Tencor soared 23 percent to $66.30 after the semiconductor equipment maker agreed to be bought by Lam Research in a $10.6 billion deal. Lam rose 9.2 percent to $76.57.
Ferrari rose as much as 17.2 percent to $60.95 on its debut on the New York Stock Exchange. Fiat, which owns 90 percent of Ferrari, fell 2 percent to $15.60. Chipotle fell 7.7 percent to $651.22 a day after the burrito chain posted disappointing third-quarter results.
VMware sank 14.5 percent to $58.77 after the virtualization software maker forecast current-quarter revenue below estimates.
Yahoo was down 2.6 percent at $31.98 after the Internet company's quarterly earnings and profit missed expectations.
Advancing issues outnumbered decliners on the NYSE by 1,556 to 1,084. On the Nasdaq, 1,135 issues rose and 1,050 fell.
The S&P 500 index showed 12 new 52-week highs and one new low, while the Nasdaq recorded 26 new highs and 14 new lows.