Costco Wholesale's (COST) revenue momentum remains strong despite a fiscal second-quarter earnings miss, as the warehouse chain delivered another "standout performance" with its US comparable sales growth in February, UBS Securities said in a note emailed Friday.

The company grew its US comparable sales by 8.6% year over year in February, when the retailer sector saw soft trends amid adverse weather and weak consumer confidence, the brokerage said.

"This shows the magnitude of its share gains," UBS said. "Plus, it indicates that it's more insulated against external headwinds and macro pressures than the rest of retail."

Late Thursday, Costco reported total revenue of $63.72 billion for the 12 weeks ended Feb. 16, up from $58.44 billion a year earlier and exceeding the consensus on FactSet for $63.11 billion. The "top-line momentum remains robust," according to UBS.

Earnings increased to $4.02 per share from $3.92 a year earlier, but came in below the consensus of $4.11. Foreign exchange negatively impacted the translation of international earnings to US dollars by $0.13 per share, Chief Financial Officer Gary Millerchip said on a conference call late Thursday.

"As we look ahead to the remainder of this fiscal year, headwinds from foreign exchange look likely to continue," Chief Executive Ron Vachris told analysts, according to a FactSet transcript.

Shares of Costco fell 7% in Friday afternoon trade.

UBS said tariff risks should be "manageable" for Costco, while Vachris indicated on the call that uncertainty usually bodes well for the warehouse club operator.

"It is difficult to predict the impact of tariffs, but our team remains agile and our goal will be to minimize the impact of related cost increases to our members," Vachris said. "About a-third of our sales in the US
are imported from other countries and less than half of those are items coming from China, Mexico and Canada."