Mark Zuckerberg sold nearly $200 million worth of Meta Platforms Inc (META  ) stock last month. This was his first sale since 2021.

The Facebook founder isn't the only company honcho making moves.

• Tim Cook, the CEO of Apple Inc (AAPL  ) also sold shares this fall, shedding more than $40 million in Apple shares in October.
• Amazon Inc (AMZN  ) founder and former CEO Jeff Bezos, meanwhile, bought one single share of the company he founded, his first purchase in 20 years.
• JPMorgan Chase & Co. (JPM  ) disclosed in a filing that CEO Jamie Dimon intends to sell a part of his stake in the company.

There are plenty of other reasons an executive with millions of shares might sell. Perhaps they want to buy a new house, or need money for tax purposes; maybe a significant donation is in the works. The adage goes, there are plenty of reasons to sell, but only one reason to buy.

One of the more obvious reasons to sell stock, at least in Zuckerberg's case, comes amid an impressive comeback in Meta's stock, with the company up more than 155% year-to-date.

From the fall of 2021 to the fall of 2022, Meta's stock crashed more than 70% as investor concern grew regarding rising interest rates and a slowing advertising environment.

But, this year, investors have been excited about the American economy holding up better than expected, as well as what artificial intelligence (AI) could mean for large tech companies like Meta.

Microsoft Inc (MSFT  ) and NVIDIA Inc (NVDA  ) have also had huge years as AI becomes more commonplace. Large tech stocks have accounted for a large portion of the S&P 500's gains so far in 2023, with NVIDIA leading the way, up more than 200% on the year, and Meta close behind at a little more than 155%.