Elon Musk's history with the letter X, from SpaceX to Tesla Model X and xAI

The billionaire's love of the letter can be traced back to his early entrepreneurial years

Weeks before completing his $44 billion acquisition of Twitter last year, Elon Musk said buying the social media company would speed up his ambitions to create an "everything app" called X by three to five years.

On Monday, the wealthiest person in the world made the first big move towards that intention since taking ownership of Twitter – by replacing the site's familiar blue bird symbol with an X.

Musk began crowdsourcing ideas on Sunday tweeting that he wanted to change Twitter's logo.

"If X is closest in style to anything, it should, of course, be Art Deco," he said, adding: "If a good enough X logo is posted tonight, we’ll make go live worldwide tomorrow. And soon we shall bid adieu to the twitter brand and, gradually, all the birds."

On Monday morning, Twitter chief executive Linda Yaccarino shared the new logo with the message: "X is here! Let’s do this."

"It’s an exceptionally rare thing – in life or in business – that you get a second chance to make another big impression. Twitter made one massive impression and changed the way we communicate. Now, X will go further, transforming the global town square," she added.

"X is the future state of unlimited interactivity – centered in audio, video, messaging, payments/banking – creating a global marketplace for ideas, goods, services, and opportunities. Powered by AI, X will connect us all in ways we’re just beginning to imagine."

A brief history of Musk and the letter X

While Musk has never really explained his obsession with the letter X, one of his first major projects was named x.com, the online bank he co-founded in 1999. The company merged with competitor Confinity a year later and came to be known as PayPal, which was acquired by eBay in 2002 for $1.5 billion.

"His concept for x.com was grand. It would be a one-stop everything-store for all financial needs: banking, digital purchases, checking, credit cards, investments, and loans," writes biographer Walter Isaacson in his book Elon Musk, out in September.

"In the days leading up to his takeover of Twitter at the end of October 2022, Musk’s moods fluctuated wildly. 'I am very excited about finally implementing x.com as it should have been done, using Twitter as an accelerant!' he texted me out of the blue at 3.30 one morning. 'And, hopefully, helping democracy and civil discourse while doing so.'

"He said that he would turn it into the combination of financial platform and social network he had envisioned twenty-four years earlier for x.com and he added that he planned to rebrand it with that name, which he loved."

Xs everywhere

Musk has used the letter X in many of his companies and products, from SpaceX (2002) to the Tesla Model X, first released in 2015.

In May 2020, Musk and his former partner, the musician Grimes, raised eyebrows when they revealed the name of their newborn son: X Æ A-12. Grimes explained that X was "the unknown variable" and Æ was to honour the "elven spelling of Ai (love &/or Artificial intelligence)".

She added that "A-12 [is the] precursor to SR-17, our favourite aircraft. No weapons, no defences, just speed. Great in battle, but non-violent" and said that the A is for Archangel, her "favourite song". Given Grimes's explanation, baby X Æ A-12's name would be pronounced "Zai-ah", like the name Isaiah without the first syllable.

Last year, the couple welcomed their second child, a girl named Exa Dark Sideræl Musk and known as Y.

In April, Musk merged Twitter with his firm X Corp, which was established in March. It is a wholly owned subsidiary of X Holdings Corp, also owned by Musk.

Then, earlier this month, Musk launched artificial intelligence company xAI, whose mission statement is “to understand reality”.

Musk bought the site x.com back from PayPal in 2017, saying then that it had "sentimental value".

The domain now links to Twitter's home page.