After the deal closed, a renamed Yahoo will mainly hold a stake in Chinese e-commerce giant Alibaba, which had a blockbuster day on Wall Street.
Yahoo's gains helped lift the Nasdaq 0.4% to 6,321.76 points.
The Dow Jones was almost flat at 21,182.53 points, while the broader S&P 500 fell very slightly to 2,433.79.
Verizon investors appeared more sceptical of the $4.5bn deal, which was delayed after Yahoo disclosed data breaches, falling 0.7%.
Verizon expects to cut about 2,000 jobs after its purchase of Yahoo's internet business goes through next week, according to reports.
Consumer-focused firms also closed down despite a 10% bounce for Nordstrom, which said it was considering going private.
But financial stocks outperformed, as Republicans pressed ahead with a bid to roll back financial rules imposed after the 2008 crisis.
Although the measures are unlikely to become law, the bill's success in the House signals commitment to some type of reform.
Ocwen Financial rose 2.7% after the loan servicer came under pressure from the Consumer Financial Protection Bureau, which would be seriously weakened under Thursday's measure.
Goldman Sachs closed up 1.4%, JP Morgan Chase added 1.25% and Bank of America climbed 1.6%.
The markets generally were overshadowed by political news, as UK voters headed to the polls and former FBI Director James Comey answered questions in Washington about his dealings with President Donald Trump.
Mr Trump fired Mr Comey earlier this year amid an FBI investigation into Russian ties to the Trump campaign. The move has generated political backlash and hurt the president's standing in Washington.
Yahoo stock soared 10% after shareholders approved sale of its core internet business to Verizon amid a muted day on Wall Street.