More private-equity firms have expressed interest in participating in a deal for Twitter, people familiar with the matter said on Monday.

The sources, who declined to be identified, did not name the firms.

The interest emerged after the New York Post reported Thoma Bravo, a technology-focused private equity firm, contacted the social media platform last week to explore a buyout that would challenge Elon Musk’s $43 billion offer.

Apollo Global Management is considering ways it can provide financing to any deal and is open to working with Musk or any other bidder, the sources said. Its participation would be through its credit investment platform rather than its private equity business, the sources added.

Apollo and Twitter declined to comment.

Twitter adopted a “poison pill” on Friday to limit Musk’s ability to raise his stake in the social media platform.