Jeff Bezos, the world’s richest man, ended July by selling more than $1.8 billion in Amazon stock, in what is likely his biggest cash-out ever. The Amazon C.E.O. unloaded about 900,000 shares, netting him about $1.4 billion after taxes, Forbes reported late Wednesday after Bezos submitted a filing reporting the sale to the Securities and Exchange Commission.

Bezos is expected to pump the extra cash into his private space comapny, Blue Origin, a competitor to Elon Musk’s SpaceX, which Bezos hopes will one day bring humans to the moon. In May, Blue Origin unveiled its new lunar lander in a glitzy launch event, during which Bezos outlined his ambitions to make humanity a spacefaring civilization. “The reason we go to space, in my view, is to save the Earth,” he said of his lunar ambitions the following month.

Neither Bezos nor Amazon have commented on the stock sale, nor has the Blue Origin founder confirmed that the money would be directed to his space program. But Bezos has previously said he dumps about $1 billion worth of stock each year to fund his space company. Perhaps, with Blue Origin moving toward commercial operations, the company needed even more cash.

In revealing its lunar lander last spring, Blue Origin escalated the space race between Bezos and Musk, whose SpaceX has been seen as the standard-bearer in the emerging private space industry. Each were awarded contracts with NASA earlier this week to support work on lunar lander and launch technologies. Blue Origin secured three agreements, all related to its lunar lander research. “We’ve identified technology areas NASA needs for future missions,” Jason Reuter, NASA’s associate administrator for space technology, said in a statement Tuesday. “These public-private partnerships will accelerate their development so we can implement them faster.”