Jeff Bezos, Jamie Dimon, and Mark Zuckerberg have sold stock worth about $9 billion. They might think markets can't go much higher.

• Jeff Bezos, Jamie Dimon, and Mark Zuckerberg have all been selling shares in their companies.
• The Amazon founder and JPMorgan and Meta CEOs risk sending a worrying message to markets.
• Executives sell shares for plenty of reasons, from tax and estate planning to personal expenses.

Amazon's Jeff Bezos, JPMorgan's Jamie Dimon, and Meta's Mark Zuckerberg have all sold big chunks of shares in their own companies. How come?