When Elon Musk promised to back Tesla’s resale value guarantee program with his own fortune or to pay back SolarCity’s debt himself if needs be, some criticized that if it came to it, it would be difficult for him to do so since his fortune is mostly tied to those companies.

There was always his stake in SpaceX, his rocket company, but the value of it and his precise stake in the company was unknown… until today.

New documents filed with the FCC for SpaceX’s planned satellite constellation revealed his exact stake in the company, which could technically be worth more than his stake in Tesla.

Tesla being a publicly traded company, its value and Musk’s stake in the company have been public since 2010.

The company’s stock took a tumble over the past few months and Musk’s roughly 22% stake in the company, or 31,100,644 shares, is currently worth $5.7 billion at today’s close of $183.93.

It has so far been believed to be the bulk of Musk’s fortune, at least according to most estimates by the likes of Forbes or Bloomberg.

SpaceX officials have disclosed in the past that Musk has a controlling share of the company, but having the majority of the votes doesn’t mean that he owns a majority of the shares. Therefore, despite some public valuation of the company through Google and Fidelity’s investment in the space exploration venture valued at roughly $15 billion, it was never clear what Musk’s stake is worth exactly.

Today, SpaceX filed with the FCC to obtain the rights to operate a massive constellation of 4,400 satellites to offer internet services from orbit, a plan that was announced last year.

In the filing, SpaceX disclosed Musk’s stake in the company which surprisingly stands at 54%:

“SpaceX is a privately held company in which the sole shareholder who is the beneficial owner of a 10% or greater interest is Elon Musk, as trustee of a private trust. Mr. Musk’s trust currently owns 54% of the outstanding stock of SpaceX and has voting control of 78% of the outstanding stock of SpaceX. Mr. Musk, a U.S. citizen, can be contacted at the following address: 1 Rocket Road, Hawthorne, CA 90250.”

If we are to believe Fidelity’s valuation of $15 billion, Musk stake in SpaceX is worth $8.1 billion.

It may give some more value to comments like this one he made last week:

@davidtayar5 Tesla will def absorb SolarCity debt. Altho extremely unlikely, I would pay it personally if need be. Debts must be honored. — Elon Musk (@elonmusk) November 5, 2016

While we are on the subject of SolarCity’s debt, tuned in tomorrow afternoon for our special shareholders meeting coverage of the vote on the SolarCity-Tesla merger.

Featured Image: Elon Musk, CEO of Tesla Motors, reacts to a reporter’s question following the electric automaker’s initial public offering on Nasdaq, Tuesday, June, 29, 2010 in New York. (AP Photo/Mark Lennihan)

FTC: We use income earning auto affiliate links. More.

Subscribe to Electrek on YouTube for exclusive videos and subscribe to the podcast.