Amazon founder and CEO Jeff Bezos sold 1 million shares in his company, whose stock is at an all-time high.
According to a Friday SEC filing, Bezos sold the shares starting on Nov. 1 at an average price of just under $1,100 each.
The sales began shortly after a strong earnings report pushed Amazon’s stock up by more than 8%. Bezos’s net worth surged above $90 billion, once again making him the richest person in the world as of Oct. 27. Over the past year, Bezos has jockeyed for the top spot with Microsoft founder Bill Gates.
Get Data Sheet, Fortune’s technology newsletter.
Bezos, according to CNN Money, has sold large stakes in his own company twice before in recent years, but still owns about 16% of Amazon, which is now one of the five largest companies in America by market value.
From one angle, Bezos’ steady selloff of Amazon stock could simply be seen as part of the same sort of diversification strategy a typical investor might pursue, since the company is performing well. But the sales could also reflect caution about the future of the broader stock market, which has experienced a historically long bull run. Despite the lack of negative indicators, that endurance in itself has begun to invite questions about how much longer the good times can last.
