An analyst downgraded The Finish Line Inc.'s stock on Wednesday, saying that the Indianapolis-based sneaker and athletic clothing retailer will likely continue to lose share to rival Foot Locker.

Finish Line shares slid 4.3 percent Wednesday after the downgrade, falling $1.06, to $23.45 per share.

Sam Poser of Birmingham, Ala.-based investment firm Sterne Agee & Leach said in a report to clients that Foot Locker had better revenue at stores open at least a year during the first quarter than Finish Line did. Finish Line also appears to be trailing its competitor in the second quarter.

This metric is an important gauge of a retailer's health because it excludes results from stores recently opened or closed.

Poser said in that much of Finish Line's same-store revenue strength came from sales in the basketball category, in particular sales of Michael Jordan products. The analyst said this makes up about 35 percent of Finish Line's business, compared with 45 percent of Foot Locker's business.

Poser is also concerned about the Finish Line's investments in new store concepts, saying that the company has been overly anxious to roll out the concepts but needs to do more testing on in-store layouts to see if they are the proper format.

"We believe that Finish Line's new store ideas are great, but the apparent lack of patience by management will likely continue to result in limited to no flow-through to the bottom line even with strong same-store sales," he wrote.

Poser lowered Finish Line Inc.'s rating to "Underperform" from "Neutral" and set a $20 price target.

Finish Line shares are down 10 percent from their 52-week high of $26.16 in late March. They traded as low as $17.80 in mid-September.