US stocks fall; DuPont-Dow Chemical merger talks limit losses

US stocks finished firmly lower Wednesday following a volatile session as merger talks between Dow Chemical and Dow member DuPont limited the Dow's decline.

The swings in share prices roughly tracked those in oil, which rallied at mid-session before closing at fresh seven-year lows. Falling commodity prices, along with a surprise rally in the euro, have rattled investors.

"The currency markets and the oil markets have been driving the positioning in equity markets and that's been mostly selling," said Michael James, managing director of equity trading at Wedbush Securities.

The Dow Jones Industrial Average dropped 75.70 points (0.43 percent) to 17,492.30. The intraday swing of the blue-chip index was more than 350 points.

The broad-based S&P 500 shed 15.97 (0.77 percent) to 2,047.62, while the tech-rich Nasdaq Composite Index tumbled 75.38 (1.48 percent) to 5,022.87.

DuPont and Dow Chemical both jumped 11.9 percent on prospects of their combining into the world's biggest chemical company, with annual sales totalling more than $90 billion.

Yahoo dropped 1.3 percent after announcing a retreat from plans to hive off its Alibaba stake and instead seek a "reverse spinoff" of its core Internet properties.

Technology stocks were generally weak. Apple fell 2.2 percent and Amazon, Facebook, Microsoft and Google parent Alphabet all lost between 1.4 percent and 1.9 percent.

Big-box retailer Costco Wholesale tumbled 5.4 percent after net income for the quarter ending November 22 fell 3.2 percent to $480 million due to a one percent fall in comparable sales.

Yoga-gear retailer Lululemon Athletica dropped 13.1 percent after forecasting fourth-quarter net income of 75-78 cents per share, below the 86 cents projected by analysts.

Gaming giant Wynn Resorts surged 13.2 percent on news that chief executive Stephen Wynn bought one million shares on the open market, lifting his stake to about 11 percent.

Auto service chain Pep Boys rose 0.2 percent after endorsing a takeover offer by Carl Icahn of $15.50 a share as preferable to a pending deal agreed with Bridgestone for $15 a share.