Pfizer, Allergan unveil merger as US stocks dip

Pharmaceutical heavyweights Pfizer and Allergan unveiled a record-setting $160 billion mega-merger Monday as US stocks finished modestly lower.

US giant Pfizer said its combination with the smaller Ireland-based Allergan would boost its offerings, permit $2 billion in operational savings and enable Pfizer to enjoy a much lower tax rate in Ireland. If finalized, the deal will be the biggest pharmaceutical merger ever.

Allergan dropped 3.4 percent while Pfizer was the biggest loser in the Dow, declining 2.6 percent.

The Dow Jones Industrial Average fell 31.13 points (0.17 percent) to 17,792.68.

The broad-based S&P 500 dipped 2.58 (0.12 percent) to 2,086.59, while the tech-rich Nasdaq Composite Index lost 2.44 (0.05 percent) at 5,102.48.

Monday's session "was very quiet with some market participants likely getting a head start on the Thanksgiving holiday," Briefing.com said.

"With that in mind, it wouldn't be surprising to see below average trading volume for the remainder of the week."

US markets will be closed Thursday for the holiday, and hold shortened trading sessions Friday.

Tyson Foods surged 10.2 percent after reporting an 88 percent rise in fourth-quarter earnings to $258 million and predicting another record year in fiscal 2016.

GameStop fell 4.2 percent after the video-game retailer announced a drop in third-quarter sales and lowered its full-year earnings forecast.

Electronic Arts, a leading developer of video games, shed 4.8 percent.

Amazon jumped 1.6 percent as it unveiled additional holiday sales promotions on electronics, toys, kitchen appliances and other goods.