Before Elon Musk was the space and electric car titan he is today, he was a young entrepreneur with a few software related ideas. One of those ideas was X.com, the online banking startup he founded in 1999 that went on to become PayPal.

Now, Musk has bought back that single character domain name, which PayPal has owned since the two companies merged in 2000. The purchase was first spotted by Domain Investing.

Musk confirmed the purchase Monday night on Twitter:

Musk served as PayPal's CEO for about a year before being ousted by the company's board in 2001 following a disagreement with company co-founder and chief technology officer Max Levchin. He retained his 11 percent stake in the company, however, and earned about $165 million when it was purchased by eBay shortly after its 2002 IPO.

It's not clear how much Musk's former company charged him to buy back the domain. For comparison, the single letter Z.com sold for about $6.8 million in 2014, according to Domain Investing.

Other simple domains have sold for even more: Belgium-based Interbrew purchased Beer.com for $7 million in 2004; online company Fund.com bought its domain for $10 million in 2008.

For Musk, buying the domain name for "sentimental value" might be the equivalent of dropping a few million bucks on what is essentially a vanity plate--for a car that will stay in the garage. Or it's possible that he has another plan for the domain sometime in the future. It wouldn't be unlike Musk, who often buries Easter eggs in his products, to turn the page into some sort of nostalgic tribute for his supporters to find on their own.

There's currently no website at X.com--visiting the domain brings up a blank page. Maybe when Musk takes a break from launching reusable rockets, rolling out the Model 3, and boring tunnels under Los Angeles, he'll put some time into a new project.

Published on: Jul 11, 2017