Costco earnings up, but not enough for Wall St.

Costco Wholesale net income rose 3% in the third-quarter as the warehouse club operator's sales and membership fees improved.

A key sales figure rose both in the U.S. and abroad, but its earnings fell short of Wall Street expectations. Its shares slipped in pre-market trading Thursday.

Costco's stores offer members the ability to buy items in bulk at low prices.

Net income for the 12 weeks ended May 11 rose 3% to $473 million, or $1.07 per share. That compares with net income $459 million, or $1.04 per share. Analysts expected $1.09 per share, according to FactSet.

Revenue rose 7% to $25.79 billion from $24.08 billion last year. Analysts expected $25.68 billion.

Revenue in stores open at least one year rose 5% in the U.S. and 3% internationally. Excluding gas prices and foreign currency fluctuation, the figure rose 6% in the U.S. and 8% internationally.

Costco, based in Issaquah, Wash., operates 655 warehouses, including 464 in the United States and Puerto Rico, 87 in Canada, 33 in Mexico, 25 in the United Kingdom, 19 in Japan, 10 in Taiwan, 10 in Korea, six in Australia, and one in Spain.

Its shares were trading between $112.85 and $113.80 ahead of market opening today, down from the previous day's close of $113.87.