The Nasdaq finished above 5,000 last night on Wall Street for the first time in 15 years, capping a long-running recovery in the exchange after the dot-com bubble burst spectacularly in 2000.
The tech-rich Nasdaq Composite Index jumped 44.57 points (0.9%) to 5,008, finishing above 5,000 for only the third time in its history.
Both the Dow Jones Industrial Average and the S&P 500 struck new records as well, as US markets marched ahead in a six-year bull run.
The Nasdaq is still about 40 points below its all-time closing high of 5,048.62, on March 10, 2000.
Yesterday's gains came on a stream of merger announcements, including the $16.7 billion acquisition of Freescale Semiconductor by NXP Semiconductor, in a deal that links two Nasdaq companies.
Shares in NXP jumped 17.3%, while Freescale rose 11.8%.
The gains were spread well among other Nasdaq tech titans: Intel (up 2.4%) and Cisco Systems and Google (both up 2.3%). Apple, the biggest US company by market capitalisation, rose 0.5%.
Biogen, part of the Nasdaq's wave of biotech companies, gained 1.5%, while Facebook, the social networking giant, added 1%.
Yesterday's gains followed a buoyant February for US stocks thanks to improving economic data, solid corporate earnings and continued central bank liquidity.
Tesla Motors was one of the few prominent Nasdaq companies to falter, losing 3% on negative analyst reports.