ISSAQUAH, Wash. — Jeff Brotman, cofounder of Costco Wholesale Corp. and the company’s chairman, died in his sleep earlier this month at age 74. Brotman helped build Costco into a global retailing powerhouse and was prominent in Puget Sound-area philanthropic and civic circles.

“The thoughts of Costco’s board, management and employees are with Jeff’s wife and family,” Costco said in a statement.

Brotman’s brother, Michel Brotman, told the Seattle Times that the cause of death was not immediately known and came as “a complete shock for everyone.”

On the night before he died, Brotman attended a dinner for about 2,000 Costco warehouse managers from around the world who were gathered in Seattle, his brother told the newspaper.

Brotman and cofounder and former chief executive officer Jim Sinegal helped mold Costco into one of the largest and most successful retailers in the world.