Goldman Sachs analyst Alexandra Walvis downgraded Under Armour (UAA)(UA)to Neutral from Buy with a price target of $9, down from $21. The shares closed Tuesday up 13.5% to $9.15.

Under Armour's low operating margins, largely inflexible cost structure and inventory buying model, and limited brand momentum leave the company less well-positioned versus other athletic peers in the current tough environment, Walvis tells investors in a research note.

The analyst, who continues to expect athletic and casual apparel to gain market share, sees elevated near-term execution risk to the shares.