Parts of Twitter’s source code, the underlying computer code on which the social network runs, were leaked online, according to a legal filing, a rare and major exposure of intellectual property as the company struggles to reduce technical issues and reverse its business fortunes under Elon Musk.

Twitter moved Friday to have the leaked code taken down by sending a copyright infringement notice to GitHub, an online collaboration platform for software developers where the code was posted, according to the filing. GitHub complied and took down the code that day. It was unclear how long the leaked code had been online, but it appeared to have been public for at least several months.

Twitter also asked the US District Court for the Northern District of California to order GitHub to identify the person who shared the code and any other individuals who downloaded it, according to the filing.

Twitter launched an investigation into the leak and executives handling the matter have surmised that whoever was responsible left the San Francisco-based company last year, two people briefed on the internal investigation said. Since Musk bought Twitter in October for $44 billion, about 75 per cent of the company’s 7,500 employees have been laid off or resigned.

Executives were only recently made aware of the source code leak, people briefed on the internal investigation said. One concern is that the code includes security vulnerabilities that could give hackers or other motivated parties the means to extract user data or take down the site, they said.

For Twitter, the leak also comes on top of mounting structural and financial challenges. Musk has been trying to turn around the social network over the past few months by slashing costs, trying out new features and welcoming back previously banned users. But outages of the service have increased, while advertisers — the main source of revenue for the company — have been skittish about running ads on the site.

The turmoil has caused financial damage. On Friday, Musk told employees in an email that Twitter was worth roughly $20 billion, down more than 50 per cent from what he paid for it.

Musk did not respond to a request for comment about Twitter’s leaked code. GitHub declined to comment on the decision to remove the code, but posted Twitter’s takedown request on its website.