Thacher Proffitt & Wood real estate partner Donald Simone was at his desk on the fortieth floor of the World Trade Center’s south tower early on September 11, 2001, pushing to close a deal, when United Airlines flight 175 slammed into the building about three dozen floors above. “When it hit, my whole office moved,” Simone recalls. With the electricity off and ceiling tiles falling, he made his way to a stairwell and then to safety.

The attacks obliterated Thacher’s New York office, but none of the 310 Thacher attorneys and support staff who worked in the World Trade Center died on 9/11. Afterward, from borrowed offices and temporary space, the firm kept working on the securitization deals that had become its lifeblood. In fact, Thacher had its best financial results after the disaster, with profits more than doubling in just three years. “There was a sense that if we could get through [9/11], we could get through anything,” says Robert McCarthy, a former partner in Thacher’s structured finance group.