Under Armour's history from their Wikipedia page:
"The company was founded in 1996 by
Kevin Plank, a 23-year old former
University of Maryland special teams captain for the university
American football team. Plank began the business from his grandmother's basement in Washington, D.C.
Plank, who got tired of having to change out of the sweat-soaked T-shirts he wore under his jersey, noticed that his compression shorts stayed dry, which inspired him to make a T-shirt using moisture-wicking fabric for athletic performance. Major competing brands including Nike, Adidas and Reebok soon followed in Plank's footsteps with their own version of Under Armour's moisture-wicking apparel.[6]
By the end of 1996, Under Armour had generated $17,000 in revenue purely by word of mouth. In 1997, Plank had $100,000 in orders to fill and found a factory in Ohio to make the shirts. People began to take notice of the brand when a front page photo of USA Today featured Oakland Raiders quarterback Jeff George wearing an Under Armour mock turtleneck. Following that front page, Under Armour's first major sale came when an equipment manager from Georgia Tech asked Plank for 10 shirts. The deal with the Georgia Tech Yellow Jackets opened the door to a contract with North Carolina State. With positive reviews from players, word began to spread and orders began to increase. Under Armour first made a profit in 1998 and received its first big break in the 1999 Oliver Stone movie Any Given Sunday, in which Willie Beamen, played by Jamie Foxx, wore an Under Armour jockstrap. Plank sent samples of his products to the costume designer. Leveraging the release of Any Given Sunday, Plank purchased an ad in ESPN The Magazine. The ad generated close to $750,000 in sales, and nine years after starting the company, Plank finally put himself on the payroll."