Under Armour shares fell a little bit after Jordan Spieth didn't win the British Open

Under Armour shares are up about 1.8% on Monday.

But they were up about 2.4% earlier in the day as one of the company's most popular young athletes - golfer Jordan Spieth - was making a run at winning the British Open, which would have been this third major win of the season. (Spieth previously won both The Masters and the US Open.)

On the 17th hole on Monday, however, Spieth missed a birdie putt that would've given him a share of the lead heading into the tournament's final hole. And this missed putt sent Under Armour shares heading a bit lower.

Spieth later missed a putt on the 18th and finished behind a three-way tie for the lead.

Spieth winning the British would've put him in line to win golf's Grand Slam at next month's PGA Open, a feat that hasn't been accomplished in golf's modern era.

You can follow all of BI's coverage of the British Open on our sports page here.

But as for Under Armour shares, they were off just a little bit after Spieth's round.