Ex-Microsoft CEO Steve Ballmer has revealed he’s taken a four percent stake in Twitter, in a move that makes him a bigger shareholder than new CEO Jack Dorsey.

“Glad I bought 4% past few months,” Ballmer tweeted from a newly verified account. His tweet paid tribute to Twitter’s new ‘Moments’ feature, as well as last week’s decision to make Dorsey the company’s new permanent CEO.

Good job @twitter,@twittermoments innovation, @jack Ceo, leaner, more focused. Glad I bought 4% past few months. Like @alwaleedbinT move too

— Steve Ballmer (@Steven_Ballmer) October 16, 2015

Ballmer’s stake surpasses the three percent stake of Dorsey, and was worth $840 million at the close of Friday trading, based on Twitter’s current $21 billion valuation. He’s not the biggest shareholder though – co-founder Evan Williams holds the largest stake at 7.5 percent, while Saudi Arabia’s Prince Alwaleed bin Talal is believed to hold a 5.2 percent share, according to Thomson Reuters data. Before admitting he’s bought into Twitter, Ballmer made an earlier tweet from his new account saying he was expecting to see “progress” under Dorsey.

I think @twitter is remarkable. There is amazing chance to innovate and grow. Excited to see progress with @jack as CEO Impressive dude! — Steve Ballmer (@Steven_Ballmer) October 6, 2015

Ballmer’s admission that he owns part of Twitter may have been tactical – giving that he himself is backing the beleaguered firm, its stock price swiftly rose by 5.6 percent on Friday to $31.34, just hours after his tweet.

While $840 million might seem like a big investment, we should note that it’s mere pocket change for someone like Ballmer. As well as owning the Los Angeles Clippers basketball team, Ballmer is said to have a personal fortune of around $21.5 billion, him the 35th richest person in the world according to Forbes.

Despite Ballmer’s vote of confidence, it remains to be seen if Twitter can pull itself out the mire, having struggled to sustain growth in recent years. Ballmer may not be the best soothsayer after all, having presided over a significant decline in Microsoft’s share price during his 14 year tenure of that company, and famously laughing when Apple unveiled its first iPhone.

At least one analyst was confident though. James Cakmak of Monness, Crespi, Hardt, & Co., Inc., told Reuters that Ballmer’s involvement was a sign that Twitter is finally getting on the right track.

“I think it’s just another point of evidence that the step that they are taking to redirect the business toward growth is resonating,” Cakmak explained.

Twitter has made a number of announcements since Dorsey was confirmed as CEO last week, the biggest being its decision to lay off around eight percent of its staff. In addition, its just hired former Google executive Omid Kordestani as its new executive chairman.

Photo Credit: Microsoft Sweden via Compfight cc