At 11:15 a.m. on July 29, Irish property developer Michael O’Flynn realized that Blackstone Group LP was trying to gain control of his real estate empire, which includes the country’s tallest residential tower.

Ten weeks earlier, the private equity firm had bought $2.4 billion of loans to O’Flynn’s companies and the developer personally. Coming out of a meeting, he learned Blackstone was demanding the immediate repayment of $21.3 million of personal loans secured on his shareholdings—even though he wasn’t in default. By the end of the day he had lost control of the business he’d spent more than 30 years building.