Millard “Mickey” Drexler, the fashion genius whose ability to spot trends reshaped how Americans dress, has a humbling admission. He missed what might be the biggest trend of all—how quickly technology would change the retail industry.

“I’ve never seen the speed of change as it is today,” the 72-year-old chairman and chief executive of J.Crew Group Inc. said in an interview at his New York office. “If I could go back 10 years, I might have done some things earlier.”

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