Under Armour will be deleted from the S&P 500 stock index before the start of trading on June 21 and be added to the S&P MidCap 400, S&P Dow Jones said.

The S&P 500 tracks the performance of 500 large companies listed on U.S. stock exchange.

The changes are being made to “ensure each Index is more representative of its market capitalization range,” S&P Dow Jones said in an announcement.

“All companies moving from the S&P 500 to the S&P MidCap 400 are more representative of the mid-cap market space, and all companies moving from the S&P MidCap 400 to the S&P SmallCap 600 are more representative of the small-cap market space,” the announcement continued.

Shares of Under Armour have lost nearly half their value this year.

Under Armour and IPG Photonics will replace Trinity Industries, Inc. and Yelp, Inc., respectively, in the S&P MidCap 400. Urban Outfitters, Inc., is also being downgraded, as part of the announced changes, from the S&P MidCap 400 to the S&P SmallCap. 600.

Photo courtesy Under Armour