Under Armour shares took a hit Monday, and "Fast Money" traders contended the once-popular stock's prospects may not improve soon.

The athletic apparel maker's stock slid more than 5 percent after Morgan Stanley kept its "underweight" rating on the stock and cut its price target. Under Armour athlete Jordan Spieth's collapse at the Masters on Sunday may not have helped.

In its note, Morgan Stanley said women's apparel growth may not meet Under Armour's expectations. Trader Brian Kelly agreed that the segment may pose a problem.

"I actually do think this is a good call on Morgan Stanley's part, and I would get out. I would take some profits," he said.

Trader Guy Adami noted that Under Armour shares have been heavily shorted. He believes that, if Morgan Stanley's assessment is right, a short squeeze could drive the stock higher after Under Armour posts results later this month.

Other athletic apparel maker stocks dipped Monday with Under Armour. Lululemon and Foot Locker shares each fell about 4 percent on the day.

Trader Karen Finerman, a Foot Locker shareholder, said she bought more of the stock on the slide. She called the movement "so far overdone."

Trader Pete Najarian added that Lululemon's stock looks appealing on its weakness. The company's shares have climbed nearly 17 percent this year.

Disclosures:

Pete Najarian

Long AAPL, BAC, BMY, DIS, DISCA, GE, KMI, KMI.A, KO, LUX, MRK, PEP, PFE, SAVE, VIAB Long Calls: AAL, AMAT, AGN, AKS, AMJ, BAC, BAX, BBBY, CL, CRM, DAL, EBAY, ECA, EGO, ENER, GRPN, HAIN, IBM, KBH, KO, KSS, LC, MDLZ, MET, MSFT, NLNK, POT, RIG, SBUX, SCHW, SLV, SLW, SPG, TCK, UAL, WYNN, XOM, YHOO, ZIOP, EWZ, GDX. Long Puts: DB, HES, MS, PBR, RY, VLO

Brian Kelly

Brian Kelly is long BBRY, Bitcoin, GLD, SH, SLV, TLT, US Dollar, UUP, Yen; he is short Aussie Dollar, BLK, British Pound, CS, DB, Euro, EWA, EWH, FRC, Hong Kong Dollar, UBS, SPY, Yuan, 5-Year Note Futures

Karen Finerman

Karen is long BAC, C, FL, GOOG, GOOGL, JPM, LYV, KORS, M, SEDG, SPY puts, URI. Her firm is long ANTM, AAPL, BAC, BOKF, C, C calls, GOOG, GOOGL, JPM, JPM calls, KORS, LYV, M, MOH, NRF, PLCE, SPY puts, URI, her firm is short IWM, MDY. Karen Finerman is on the board of GrafTech International.

Guy Adami

Guy Adami is long CELG, EXAS, GDX, INTC, Guy Adami's wife, Linda Snow, works at Merck.