The benchmark S&P 500 breached the 2,700-mark for the first time shortly after open on Wednesday, while the Nasdaq and the Dow hit records on a strong run in technology stocks.
Oracle and IBM rose about 3 percent following brokerage upgrades, helping the S&P technology index gain about 1 percent.
U.S. stocks kicked off 2018 on a strong note on Tuesday, with the S&P 500 and the Nasdaq closing at record levels.
"The sentiment is very much positive. We had a strong start and we are likely to see a follow through in the near-term," said Scott Brown, chief economist at Raymond James in St. Petersburg, Florida.
At 9:39 a.m. ET, the Dow Jones Industrial Average was up 30.89 points, or 0.12 percent, at 24,854.9 and the S&P 500 was up 4.61 points, or 0.17 percent, at 2,700.42. The Nasdaq Composite was up 21.37 points, or 0.3 percent, at 7,028.27.
However, gains in the technology sector were limited by a 2 percent drop in Intel following a report that its processor chips had a fundamental design flaw.
Rival chipmaker Advanced Micro Devices was up about 5 percent. Other chipmakers Nvidia and Micron were also higher.
The Federal Open Market Committee is set to release minutes from its December meeting, when the central bank raised interest rates for the third time in 2017.
Investors will parse the minutes, due at 2:00 p.m. ET, for hints on rate tightening action in the coming months and the impact of the U.S. tax overhaul on the economy and inflation.
The odds of a March rate hike are at 56.3 percent level, according to the CME Group's Fedwatch tool.