The sportswear maker, in the midst of a convincing turnaround this year, blew away Wall Street estimates in third quarter earnings reported this week and injected a dose of optimism into the stock market.
Under Armour shares were up an overwhelming 27.82 percent.
The broader index seesawed for much of the day but a late afternoon rally lifted it to a gain of 1.55 percent.
While few companies this quarter have been rewarded for good financial results, Under Armour scored the trifecta: It beat estimates on earnings and revenues, and it raised forward guidance on profits by nearly 20 percent.
Akamai Technologies also soared today on strong earnings.
The online content delivery company beat earnings estimates by more than 10 percent and revenues by more than 1 percent on the strength of demand from video-gamers and cyber-security customers.
The stock was up 16.92 percent.
Tech services provider Cognizant Technology, on the other hand, saw its stock fall 3.9 percent — the biggest decline on the index — after it lowered fourth quarter guidance because of weak demand from bank customers.
The broader technology sector rallied strongly with Twitter (4.54 percent), Facebook (2.91 percent) and Alphabet Inc. (1.58 percent) posting gains while Amazon.com (-0.55 percent) and Adobe Systems Inc. (-0.56 percent) had small losses.
Chipmaker NVIDIA Corp. continued to play the tech sector pinball. Down 6.39 percent then up 9.36 percent.
Telecom giant Comcast continued to draft off its strong earnings report last week and what appears to be a shift in the market to more defensive stocks with dependable outlooks.
The stock gained 4.78 percent and is up more than 10 percent since it reported earnings last week.