Costco Wholesale Corp. said late Thursday its May sales rose 16.9% to $18.23 billion. Same-store sales rose 15.5%, the company said, with online sales up 6.3%. Costco stock rose 0.3% in the extended session Thursday, after ending the regular trading day up 6.7%.

Market Pulse Stories are Rapid-fire, short news bursts on stocks and markets as they move. Visit MarketWatch.com for more information on this news.