Investors gave a jolt to shares of Grill Concepts Inc. Friday after the company reported robust sales but a quarterly loss.

Grill Concepts, which owns the Daily Grill and the Grill on the Alley restaurants, reported a second-quarter loss of $39,000 (minus 1 cent per share) compared to a profit of $1.5 million (26 cents) for the same period a year earlier. The company blamed an increase in expenses as well as charges for stock options for the dip in profit.

However, revenues for the Los Angeles-based restaurant owner were up 22 percent to $22.8 million thanks mainly to an 11 percent growth in same-store sales for the quarter, the company said.

The company earlier trimmed earnings from two previous quarters and for the fiscal year 2006 after it found accounting errors regarding its $2.8-million purchase of Hotel Restaurant Properties Inc. last fall.

Shares in Grill Concepts were up 52 cents, or 9.6 percent, to $5.95 in afternoon trading Friday afternoon on the Nasdaq.