The Nasdaq Composite gained 41.03 points, or 0.37 percent, to 11,170.75 at the opening bell. The S&P 500 opened higher by 5.05 points, or 0.15 percent, at 3,387.04.
The tech-heavy Nasdaq Composite in June was the first of the three major US stock indexes to reclaim record highs as investors gravitated to stocks including Amazon.com and Netflix seen as stay-at-home winners from COVID-19 lockdowns.
It has taken the benchmark S&P 500 about two months longer as surging COVID-19 cases sparked fears of another round of shutdowns that would again cripple business activity.
On the day, the S&P 500 gained 0.4 percent putting it up about 55 percent from March's lows.
The Nasdaq gained 0.6 percent to hit a record high and the Dow Jones Industrials, which is still about 6 percent off its February highs, added 0.1 percent.
Of the 11 major S&P 500 sectors, the technology index, which includes Apple Inc and Microsoft Corp, has climbed about 25 percent this year, while the consumer discretionary index, which includes Amazon, has jumped 22 percent.
Closing at a record high, according to a widely accepted definition, would confirm that the S&P 500 has been in a new bull market since its pandemic low on March 23.