A few days before the Brexit vote, Mark Curtis thought about pulling his money from a £3.9 billion ($5.1 billion) U.K. commercial real estate fund run by Henderson Group. But then he changed his mind, convinced that Britain would remain in the European Union and the property market would keep humming. Curtis, who lives in Bristol and works in IT, again thought about selling on June 24, after waking up to the news that the election results went the other way. Again he decided to hang on, believing it was best not to sell into a falling market. Then other real estate funds stopped allowing investors to withdraw their investments. That scared him.