Jeff Bezos is one of the world's richest people. So, it's perhaps no surprise that headlines pop up when he sells billions worth of Amazon stock. But the reason behind the sale might prove most important to Bezos -- and to those who do business with him.

Since January 31, Bezos has sold $4.1 billion in Amazon stock, CNBC is reporting after reviewing the company's SEC filings. The transactions were made as part of a 10b5-1 trading plan, which allows company insiders to sell their corporate stock.

Bezos's move wasn't necessarily a surprise. Last August, for instance, he sold $2.8 billion in Amazon shares. He also sold a little less than that in previous years.

Of course, neither Amazon nor Bezos has commented on why the company's chief executive has sold that much stock. And, because of SEC regulations, there's no requirement for any corporate executive to share that information. But Bezos has provided some hints at what might've informed his recent sales.

For one, Bezos has made clear that he will use $1 billion in Amazon stock each year to fund Blue Origin, his company that sends rockets into space and may eventually play a role in bringing people to Mars.

It's an important point. Along with Elon Musk's SpaceX, Blue Origin is trying to revamp how people go to space, and how missions are launched to space. It also creates an entire industry for smaller businesses to capitalize on space travel. For every rocket, after all, there's need for fuel and other resources. The sheer amount of technology, data-safeguarding, security, and other services needed just to carry out Blue Origin's mission is critical.

While we can't be sure whether Bezos has invested just $1 billion from the cash haul into Blue Origin or more, it tells everyone even on the fringe of space travel that he's still investing there -- and companies can capitalize.

Aside from that, Bezos has historically used funds from his stock sales in pursuit of charitable activities. Through his Day One Fund, Bezos has used his vast wealth to combat homelessness and improve education in low-income communities. It's possible, though again unconfirmed, that at least some of his newly acquired cash could be put toward the Day One Fund.

Beyond that, it's hard to say what Bezos might ultimately do with his new cash. Sure, he paid some taxes, but there may be more cash left over. It should be interesting to keep an eye on this and see if Bezos has some plans for it that go above and beyond his existing investments -- and could ultimately become new opportunities for other business leaders.