(Reuters) -Costco Wholesale ( COST ) missed market expectations for fourth-quarter revenue on Thursday on cautious spending by budget-conscious customers at its membership-only stores, as well as an impact from lower gasoline prices.

Shares of the company were down marginally in volatile extended trading. They have gained about 37% so far this year.

While ultra-low prices on groceries and other kitchen staples is driving demand for essential products, consumer spending on big-ticket categories such as furniture, home and sporting goods has been choppy, hurting sales at Costco's warehouses.

The company's same-store sales are also taking a hit from lower gasoline prices, which squeeze their margins. They grew 5.4% in the reported period, compared with a 6.6% rise in the third quarter.

Costco reported quarterly revenue of $79.70 billion, compared with analysts' average estimate of $79.97 billion, according to LSEG data.