In February, high-end Miami Beach real-estate agents buzzed that billionaire hedge-fund manager Ken Griffin had purchased the longtime Star Island home of Russian-born hospitality magnate Vladislav Doronin for $120 million, a record for Miami-Dade County. When the deal finally recorded March 6, however, the buyer was cited in the press as a limited liability company tied to a different longtime Chicagoan—healthcare-technology entrepreneur Michael Ferro.

Local spec-home developer Todd Michael Glaser, who has plans for a new mansion on nearby North Bay Road, said he was relieved that it was Ferro’s name and not Griffin’s attached to the big-ticket deal. He has concerns, he said, that Griffin’s track record of aggressively purchasing the country’s highest-end homes could lead to a damaging perception in the market—that Griffin’s the only buyer in town.