 Shares of Under Armour Inc. UA, -7.14 UAA, -7.06 slumped 2.6 in premarket trading Friday, despite a rally in the broader stock market, as the athletic apparel and gear maker suffered collateral damage from rival Nike Inc.s NKE, -3.41 a disappointing earnings report. Also getting hit, yoga apparel and gear maker Lululemon Athletica Inc.s stock LULU, -2.95 slid 2.6 ahead of the open. 