The Dow Jones Industrial Average exceeded 16,000 for the first time in its history on Monday as the prospect of further Federal Reserve stimulus boosted investor appetite for risky assets.
The S&P 500 index also hit a record high, climbing above 1,800 early in the day, then crisscrossing the milestone several times.
The Nasdaq Composite hovered near 4,000, a height it has not reached since September 2000.
The gains began late last week after Janet Yellen, who is likely to succeed Fed Chairman Ben Bernanke, defended the central bank's bond-buying program at her confirmation hearing, and suggested it would maintain the stimulus until the economy was on a surer footing.
On Monday, Boeing Co. and Tyson Foods Inc. were among the companies making the biggest gains on the Dow. Boeing rose following the news that it had received a record number of plane orders on the first day of the Dubai Air Show. Tyson Foods attracted investors after reporting that more sales of beef and chicken at higher prices had boosted revenue.
"Fundamentals are driving this market with help from our friends at the Fed," Doug Cote, chief market strategist at ING Investment Management, told the Wall Street Journal. "The notion that this market doesn't have room to run is actually false."
The Dow has risen 22 percent and the S&P 500 has increased 26 percent since January.
The indexes closed off their highs. The Dow finished at 15,976.02, up 0.09 percent on Friday's close, while the S&P 500 slipped 0.37 percent to close at 1,791.53. The Nasdaq edged down 0.93 percent to 3,949.07.