Aug 20 (Reuters) - Specialty retailer Wet Seal Inc (WTSLA.O) posted a lower-than-expected quarterly profit on a fall in gross margins and forecast third-quarter earnings below Wall Street expectations.

Wet Seal womenswear - Photo: www.wetseal.com

For the second quarter, Wet Seal, which runs the Arden B. chain in addition to its namesake stores, earned $3.1 million, or 3 cents a share, compared with $10.1 million, or 10 cents a share, a year ago.

Excluding items, the company posted a profit of 2 cents a share, below analysts' average estimate of 3 cents a share, according to Reuters Estimates.

Sales fell 9 percent to $136.4 million. Analysts on average were expecting $136.8 million.

The retailer, whose rivals include American Eagle Outfitters Inc (AEO.N) and Gap Inc (GPS.N), forecast a third-quarter profit of 2 cents to 5 cents a share on sales of $138 million to $142 million.

Analysts on average expect a third quarter profit of 6 cents, before special items, on revenue of $140.7 million.

The retailer forecast a decline of 6 percent to 9 percent in third-quarter same-store sales.

The company said it would open three Wet Seal stores and close one Arden B store.

Shares of Foothill Ranch, California-based Wet Seal closed at $3.32 Thursday 20 August on Nasdaq. (Reporting by Vidya Lakshmi in Bangalore; Editing by Vinu Pilakkott)