When the market is at record highs, that's a great time to convert paper wealth to cash dollars. Just ask JPMorgan's Jamie Dimon, Meta's Mark Zuckerberg, or Amazon's Jeff Bezos — all of whom have been selling a lot of stock of late.

Why it matters: It makes sense even for billionaires to diversify out of having the overwhelming majority of their wealth in a single stock. Now's a great time to do just that.

By the numbers: Between them, the three moguls have sold $9.3 billion of stock in less than a month, per Jonathan Moreland of Insider Insights.

• Dimon sold $150 million of JPMorgan shares on Feb. 22.
• Zuckerberg sold $661 million of Meta shares between Jan. 31 and Feb. 21.
• Bezos sold $8.5 billion of Amazon shares between Feb. 9 and Feb. 20.

Zoom out: Even these astonishing numbers pale in comparison to the $39.5 billion of Tesla shares that Elon Musk sold between November 2021 and December 2022, mostly to raise the cash he needed to buy Twitter.

Between the lines: When companies are growing fast or still establishing themselves, the stock market tends to frown on substantial share sales from CEOs — it's seen as a sign of a lack of faith in the stock.

• Now that these companies are firmly established as some of the most valuable corporations on the planet, however, Wall Street cares less about such personal signals. After all, at some point, every family will need to diversify its wealth.

The bottom line: For a CEO, the best time to sell your stock is when it's high and rising. That, broadly, is where the market is right now.