Twitter is worth less than half of what Elon Musk paid for it six months ago having lost more than $20bn (£16.4bn) in value, according to calculations based on a leaked memo from the billionaire. Musk suggested in memo to the social media company’s staff that it is now valued at less than $20bn. This compares with the $44bn he paid for it in October 2022. The company’s steep devaluation follows Musk’s turbulent takeover. Several large advertisers have left the platform and a major source of funds for Musk’s purchase of the company, the investment firm Fidelity, has written down the value of its stake by 56%. The measure of Twitter’s worth was based on Musk’s offer of stock grants, according to Platformer and the Information, which first reported on the memo. Generally used as way to incentivise employees, stock grants are an opportunity to buy shares that cannot be sold until a set point in time, as opposed to stock options, which - depending on the conditions applied - can be more flexible. The aim is to encourage staff to reach a set valuation by a point in time so that they can sell their shares for cash. The stock grants could be “sold every six months, based on a third party valuation”, another separate internal email to Twitter staff said. Musk’s email also said that, before a spate of high-profile, acrimonious layoffs the company had been about four months from running out of money. Twitter’s headcount has been cut from about 7,500 to about 2,000 employees, according to figures Musk put forward in December. In his latest memo, he also told staff: “I see a clear, but difficult, path to a >$250B valuation,” which would imply a tenfold increase in share value. The memo suggests the model would be similar to that which Musk, who also runs Tesla, has adopted at SpaceX, another of his companies, which allows staff to sell shares back to it. This can be a lucrative incentive if the company’s value rises significantly, but it is not as flexible as selling a listed stock.