As Amazon.com has diversified into everything from cloud services to movie production, its management team has remained remarkably stable. About a dozen of CEO Jeff Bezos’ top lieutenants have remained by his side for at least the last decade, and many for longer. That continuity has helped the company grow into new business areas.

Consider this: Mr. Bezos’ roughly 17-person senior team, known internally as the S-team, has an average tenure at Amazon of about 15 years, most of the company’s 23-year lifespan. That’s a rare degree of allegiance for a large group of executives, particularly at a technology company. Google, which has been around almost has long, has had a lot more turnover among its senior management, by comparison.