Economists and central bankers have warned about bubbles in several of the world's key property markets, but it appears investors are now expecting just one to burst in the near future.
London has been on the radar for many "short sellers" - traders who bet that a particular security will fall in price - with even the Bank of England Governor Mark Carney talking of stretched valuations in the capital. But, it now appears these hedge funds and asset managers are putting their money where their mouths are.
"U.K. homebuilders have seen their first bear raid in nearly five years as luxury London property prices stall," Simon Colvin, a research analyst at data firm Markit, said in a note on Tuesday.
Filings to the U.K. financial regulator show that it's the London-exposed housebuilder Berkeley that is peaking the most interest. Firms like Anchorage Capital Master Offshore, BlueMountain Capital Management, Gruss Capital Management and Marshall Wace have taken short positions but either declined to comment or were not immediately available for comment when contacted by CNBC.