The major domestic equity indexes chalked up record highs on Monday, helped by optimism about merger activity in combination with a hope that the Republican plan to cut corporate taxes would increase corporate earnings.

Qualcomm’s shares ended the trading day up 1.15 percent after Broadcom offered to buy the smartphone chip supplier for $103 billion in what could be the largest-ever acquisition in the tech sector. Broadcom closed up 1.42 percent.

Twenty-First Century Fox was up 9.93 percent after CNBC reported that the film and television conglomerate has held talks to sell most of the company to Walt Disney. The result was that Disney’s shares chalked a gain for the day of 2.02 percent.

Investor optimism was also fueled by a Republican proposal last week to slash the corporate tax rate to 20 percent from 35 percent and end some tax breaks for companies and individuals.

Apple rose 1.01 percent and contributed more than any other stock to the benchmark S&P 500 index’s gain.

Shares of Sprint fell 11.54 percent to a more than one-year low after it called off a merger between itself and T-Mobile. T-Mobile ended the day down 5.72 percent.

The S&P 500 energy index rose 2.2 percent on gains in crude prices after the crown prince of Saudi Arabia, the world’s largest oil exporter, tightened his grip on power through an anti-corruption purge.

In afterhours trading, Priceline saw its share price decline by 6 percent and Weight Watchers International saw its share price climb by 10 percent after both companies reported quarterly earnings.

With more than 400 of S&P 500 companies having reported, earnings for the third quarter are expected to have climbed 8 percent, compared with expectations of a 5.9 percent rise at the start of October, according to Thomson Reuters I/B/E/S.

Up 15 percent in 2017, the S&P 500 is trading at about 18 times expected earnings, according to Thomson Reuters Datastream.

Michael Kors share price closed 14.70 percent higher after the fashion accessories maker raised its 2017 revenue forecast. The stock was the largest percentage gainer on the S&P 500 index.

Advanced Micro Devices was up 7.28 percent after a report indicating that it plans to team up with Intel to form a personal computer chip unit. Intel ended 1.37 percent higher.

Approximately 6.6 billion shares changed hands on the major domestic equity exchanges on Monday, a number that was above the 6.4 billion share daily average over the last 20 sessions.