Editor's note: This brief was summarised by The Property AI Newsroom from a report by The Negotiator. Read the original article for full details.

US Investor Bill Ackman Buys 6% Stake in Rightmove as Takeover Rumours Fly

US hedge fund manager Bill Ackman has bought a 6% stake in Rightmove via his fund Pershing Square Capital Management, in a share purchase worth hundreds of millions of pounds. Investor insiders claim the move could signal a takeover challenge in the coming weeks.

A report by The Sunday Times reveals that Ackman, described as an activist investor, has built the position in the UK's largest property portal. According to investor insiders, Ackman believes Rightmove's share price is significantly undervalued following its recent shift towards AI tools and the resulting fall in its share price.

Share price rollercoaster

Rightmove's share price hit a high of £8.18 a share during the summer of 2025, but began to slide as the threat posed by AI-enabled search engines, such as ChatGPT, to its dominance of the online house-hunting market became clear. The firm's response in last November's trading results did not help, and the share price bottomed out at £4.10 a share in May this year.

The price has since begun to recover, sitting at around £5 per share, as the AI threat to Rightmove has failed to materialise in the short term.

What happens next

Ackman is reported to now own 6% of Rightmove's stock, a position from which he will either make considerable profits if the share price eventually recovers, or launch a takeover. He believes the value gap represents a chance to make significant profits.

The Sunday Times also reports that Ackman's mentor, fellow hedge fund figure Sachem Head, has been making it known to the London market that he believes the AI-prompted share sell-off of Rightmove stock has been overcooked, and is encouraging the portal to take on debt to fund share buybacks. Anonymous investors have claimed one interpretation of this is that Head thinks Rightmove is undervalued and ripe for a takeover.

Why it matters for agents

Rightmove is a core listing channel for UK letting agents and inventory clerks, and any change of ownership or strategic direction at the portal could affect pricing, products and platform priorities across the rental market. The Negotiator has approached Rightmove for comment.