Rightmove (RMV.L) shares plummeted on Monday as chief executive Peter Brooks-Johnson announced plans to step down next year after more than 16 years at the firm.
He will remain CEO until the company posts its full-year results in February 2023, which will mark six years since he took the top job at Britain's largest property website.
The outgoing chief will help find a replacement to ensure a smooth handover as the property firm's search for a successor starts, Rightmove said.
Brooks-Johnson joined the firm in 2006 and became its chief operating officer in 2013, before he took the helm in May 2017. He was previously a management consultant with Accenture and the Berkeley Partnership.
Shares in the FTSE 100 (^FTSE) company fell as much as 7.1% to 519.4p in mid-morning trade in London.
"A sharp drop in Rightmove’s shares upon news that Peter Brooks-Johnson is to step down in 2023 is perhaps the ultimate compliment to the online property portal’s boss and you can see why investors will be sorry to see him go,” said Russ Mould investment director at AJ Bell.
"During Brooks-Johnson’s tenure, which started in May 2017, the firm’s shares made it into the FTSE 100 for the very first time and provided investors with premium returns, with a 45% capital gain, compared to a mere 3% advance in the index over the same time span.”
It comes as the company, which earns the bulk of its money from estate agents listing homes, reported an operating profit of £226m ($278.8m) on revenues of £305m.
Rightmove has also returned almost £750m in cash to shareholders via dividends and share buybacks.
The CEO's departure comes as the prospect of a slowdown in the UK's housing market mounts amid the tightest cost of living squeeze since the 1970s.
"With Rightmove progressing well on its mission to make home moving easier and our strong trading from 2021 continuing into 2022, I have decided it is an appropriate time to seek a new challenge," Brooks-Johnson said.
Andrew Fisher, Rightmove chairman, said: "Peter has made a significant contribution to the success of Rightmove over the past 16 years and whilst we are disappointed that he will be leaving the business, we understand his decision."
He added: "I look forward to working with Peter to ensure a smooth transition and given Rightmove’s strong market position we are confident we will attract a high-calibre successor."
Rightmove, which launched in 2000, advertises over 90% of all UK property listed for sale. It was formed by estate agencies Countrywide, Connells, Halifax and Royal and Sun Alliance, and was initially free to list homes before it started charging in 2002.