• Strong results follow disappointments from Walmart, Target
  • Costco shares dip in extended trading in the wake of earnings
A customer shops inside a Costco Wholesale Corp. store in Miami, Florida.

Costco Wholesale Corp. once again proved itself to be one of the strongest discount chains in retail, but broader fears about the industry are hard to dispel.

Same-store sales — a key benchmark — beat analysts’ estimates in the most recent quarter, helping propel revenue and earnings above Wall Street projections.

Still, the…