The Dow and S&P 500 closed at fresh highs on Monday, following acquisitions in the pharmaceutical and apparel sectors and a rise in Dow member Apple.
The Dow Jones Industrial Average rose 26.32 points (0.14 percent) to 18,298.88, besting the prior market set on March 2 by 10 points.
The S&P 500 notched its third successive record, rising 6.47 (0.30 percent) to 2,129.20, while the tech-rich Nasdaq Composite Index jumped 30.15 (0.60 percent) to 5,078.44.
All three indices got a lift from the latest call from activist Carl Icahn for more share buybacks from Apple.
Icahn told Apple in an open letter he believes its shares are worth $240. That sent the largest US company by market capitalization up 1.1 percent to $130.19, and helped to lift the Nasdaq within 15 points of its all-time peak.
The records also came as Endo International announced an $8.05 billion acquisition deal for privately held US firm Par Pharmaceutical Holdings to strengthen its generic drugs business, the latest deal in a string of drug-industry mergers. Endo fell 5.4 percent.
Women's apparel company ANN, parent of chain Ann Taylor, surged 19.9 percent following news it will be acquired by Ascena Retail Group for about $2.2 billion. Ascena, which owns the Dressbarn and Lane Bryant chains, fell 1.09 percent.
Mace Blicksilver, director of Marblehead Asset Management, said volume was light on a day with no major economic indicators.
"There doesn't seem to be sellers coming to market so you have this quiet drift up," Blicksilver said.
Semiconductor company Altera jumped 5.7 percent following a report in the New York Post saying that it had resumed talks with potential acquirer Intel. Dow member Intel rose 1.2 percent.
Dow member Chevron fell 1.3 percent following a downgrade by Goldman Sachs.
Bond prices fell. The yield on the 10-year US Treasury rose to 2.23 percent from 2.14 percent Friday, while the 30-year advanced to 3.03 percent from 2.94 percent. Bond prices and yields move inversely.