Amazon’s deep bench still leaves key man risk

Every once in a while, Amazon.com investors get an uncomfortable reminder that Jeff Bezos isn’t immortal.

Those reminders come in different forms, ranging from a helicopter crash in rural West Texas in 2003 to news of Mr. Bezos’ pending divorce early last year. The latter wasn’t exactly life-threatening, but it did raise questions about the ownership stake by which Amazon’s sole founder still maintains a high degree of control over the now-mammoth company. That was enough to shave about 2% off Amazon’s otherwise-buoyant stock price over a three-day period.

The latest reminder came Friday with the company’s announcement that Jeff Wilke, currently chief executive of Amazon’s Worldwide Consumer division, was retiring. Mr. Wilke has been with the company for nearly 21 years and was a known confidant of Mr. Bezos—making him one of the most speculated about candidates for succession to the top job. And he doesn’t appear to be leaving for greener pastures. In a memo to staff, Mr. Wilke said he has no future job plans and wants to “take time to explore personal interests.”