• Elon Musk's net worth keeps rising.
• Musk's net worth topped $400 billion on Wednesday, making him the first person to reach that mark.
• The billionaire had already gotten $155 billion richer this year, fueled by a rise in Tesla shares.

Elon Musk just keeps getting richer. And now, he's the first-ever person to hit the $400 billion mark.

The Tesla and SpaceX CEO's net worth skyrocketed to $439.2 billion on Wednesday — an increase of about $50 billion in just one day, according to Bloomberg figures.

The jump comes after an insider share sale at SpaceX boosted the space exploration company to a $350 billion valuation, making it the most valuable private startup in the world. Musk is believed to own about 42% of the firm, NBC News reported.

Prior to the massive boost on Wednesday, Musk's net worth had already soared by an unmatched $155 billion this year, placing him at $384 billion as of market close on Tuesday, according to the Bloomberg Billionaires Index.

The index, which has not yet been publicly updated to reflect the latest jump, on Tuesday showed Musk $140 billion ahead of the world's second richest person, Amazon founder Jeff Bezos, who's worth $244 billion.

The jump comes after the world's richest person broke his wealth record of about $340 billion in late November, which had stood for just over three years.

Musk's soaring wealth also piggybacks on the postelection rally for Tesla stock. Tesla's stock has soared nearly 71% so far this year. Its market cap is $1.23 trillion.

The stock has surged since Donald Trump's victory in the US presidential election, as investors wagered the electric vehicle maker would benefit from Musk's close ties to the president-elect.

Mark Malek, Siebert's chief investment officer, previously told BI that "some sort of premium has been placed on the stock as a result of Musk's very public involvement in Trump's campaign."

Tesla could continue to make further gains. Analysts at Bank of America said in a note last week that a recent visit to the Austin factory gave them "increased confidence that TSLA is well-positioned to grow in 2025+ with its core EV business … launch of its robotaxi offering, and longer-term from its investments in Optimus."

Tesla is now significantly more valuable than Warren Buffett's conglomerate, Berkshire Hathaway, which has a market cap of just under $1 trillion.

Musk has a stake of about 13% in Tesla. His latest $439.2 billion net worth is nearly $100 billion higher than the market cap of Salesforce, valued at $344 billion.

Earlier this month, a Delaware judge slapped down Musk's mega pay package from Tesla for the second time. The company said it will appeal the ruling.

Update: December 11, 2024 — This story was updated with Elon Musk's latest net worth, which topped $400 billion.