Pfizer and Allergan weigh on markets
(Closed): Wall Street finished lower following the announcement by US drugs giant Pfizer that it would merge with Botox-maker Allergan.
Shares of Pfizer fell 2.6% after announcing the $160bn (£106bn) record takeover that will allow the company to avoid high US corporate taxes.
The Dow Jones Industrial Average fell 0.2%, or 31 points, to 17,792.6 points.
The S&P 500 ended 0.1%, or 2.6 points, lower at 2,086.59 points, while the Nasdaq was almost flat at 5,102.4.
Stephen Massocca, chief investment officer of Wedbush Equity Management, said: "We had a very large rally last week and it's not surprising to see the market correct after that."
Disappointment in the Pfizer/Allergan deal was driven by lower-than-expected savings estimates, along with regulatory hurdles and a possible delay in Pfizer's plan to split into two companies, analysts said.
Shares in Tyson Foods jumped 10.2% after reporting an 88% rise in fourth-quarter profits to $258m. Tyson also predicted another record year in 2016.
Amazon shares added 1.6% after announcing additional holiday sales on electronics, toys, and kitchen appliances.
Among the fallers, GameStop shed 4.2% after the video game retailer reported lower third-quarter sales and cut its full-year forecast.
Video games maker Electronic Arts closed 4.8% lower.
US markets will be closed Thursday for the Thanksgiving holiday, and hold a shortened trading session on Friday.