The New York stock exchange's three leading indexes fell on the trading week's first day.
The broad S&P 500 index, which on Friday rose for the ninth consecutive day, now fell 0.6 percent. The index was weighed down by declines in IT giants such as Apple and Amazon, which lost 3.2 percent and 1.9 percent, respectively.
Dow Jones industrial index fell 0.2 percent and the technology-heavy Nasdaq composite index fell 0.7 percent.
The price of crude oil fell after the oil cartel Opec+ announced that production would increase by 411,000 barrels per day from June 1. Shares in energy giants such as Chevron and Exxon Mobile fell 3.0 percent and 2.7 percent, respectively.
Berkshire Hathaway fell 5.0 percent after the announcement over the weekend that the investment company's legendary CEO Warren Buffett will leave the CEO post at the end of the year. The 94-year-old Buffett will, however, remain as chairman of the board after the turn of the year.
