Talks between Pfizer and Allergan raised the prospect of a mega-merger in the pharmaceutical industry Thursday as the broader US stock market finished slightly lower.

The Dow Jones Industrial Average dipped 23.72 points (0.13 percent) to 17,755.80.

The broad-based S&P 500 slipped 0.94 (0.04 percent) to 2,089.41, while the tech-rich Nasdaq Composite Index shed 21.42 (0.42 percent) at 5,074.27.

Allergan jumped 6.0 percent and Pfizer lost 1.9 percent after the companies disclosed that they are holding "friendly" discussions on a possible combination. A deal would run north of $100 billion in value and be the biggest of the year.

Analysts said investors continued to weigh Wednesday's Federal Reserve policy statement, which opened the door to a possible interest rate hike in December.

Thursday's subdued trade shows investors have become more comfortable with a rate hike, said Michael James, managing director of equity trading at Wedbush Securities.

Goodyear Tire & Rubber lost 4.8 percent as it reported a 10.2 percent drop in third-quarter revenues to $4.18 billion, below the $4.22 billion forecast by analysts.

PayPal fell 1.7 percent after reporting that third-quarter net income rose 28.6 percent to $301 million. Analysts said the digital payments industry faces rising competition from a wide range of players, including JPMorgan Chase and Apple.

MGM Resorts gained 4.8 percent as third-quarter profit came in at $66.4 million, up from a $20.3 million loss in the year-ago period following higher hotel occupancy and casino revenues in Las Vegas.

Companies with large downward moves followings earnings reports included Buffalo Wild Wings (-17.3 percent), GoPro (-15.2 percent) and NXP Semiconductors (-19.7 percent).

But Aetna gained 3.4 percent after raising its profit forecast and Time Warner rose 3.6 percent after reporting gains in some key subscription categories.

Bond prices fell. The yield on the 10-year US Treasury rose to 2.18 percent from 2.09 percent Wednesday, while the 30-year advanced to 2.96 percent from 2.87 percent. Bond prices and yields move inversely.