The tech-heavy Nasdaq rose as much as 0.4 % to hit a record level of 6,007.72 helped by gains in Biogen and Apple.
The index first breached the 5,000 mark on March 7, 2,000 and closed above that level two days later during the height of the tech boom. Biogen's shares jumped more than 4 % after the biotech company reported better-than-expected quarterly profit and revenue on Tuesday.
At 9:36 a.m. ET, the Dow Jones Industrial Average was up 184.02 points, or 0.89 %, at 20,947.91, the S&P 500 was up 9.71 points, or 0.41 %, at 2,383.86 and the Nasdaq Composite was up 22.27 points, or 0.37 %, at 6,006.09.
Trump promised last week to make "a big tax reform and tax reduction" announcement on Wednesday. The president has directed his aides to move quickly on a plan to cut the corporate income tax rate to 15 % from 35 %, a Trump administration official said on Monday.
Nine of the 11 major S&P 500 sectors were higher, with materials and financials in the lead.
Better-than-expected profits at McDonald's and Caterpillar helped the Dow outperform other major Wall Street indexes.
Tuesday's gains build on a day earlier rally, which was driven by the victory of centrist candidate Emmanuel Macron in the first round of the French presidential election. Polls show Macron is likely to beat his far-right rival Marine Le Pen in a deciding vote on May 7.
"The French vote and Trump's plan to slash corporate taxes to 15 % are two powerful forces that will still likely contribute to a positive trend as earnings prove to be better than expected," Peter Cardillo, chief market economist at First Standard Financial wrote in a note.
Of the 100 S&P 500 companies that have reported results so far, 77 % have beaten profit expectations, according to Thomson Reuters I/B/E/S. Over the past four quarters, 71 % of the companies had beaten estimates.
Straight Path rose 6.3 % after the company said a "multi-national telecommunications company" had offered $104.64 per share, topping AT&T's bid of $95.63 per share.
Sandwich supplier AdvancePierre Foods jumped 9.2 % after Tyson Foods said it would buy the company for about $3.2 billion in cash.
Advancing issues outnumbered decliners on the NYSE by 1,857 to 741. On the Nasdaq, 1,787 issues rose and 519 fell.
The S&P 500 index showed 57 52-week highs and two lows, while the Nasdaq recorded 114 highs and nine lows.