Marsh & McLennan Companies
US-based global financial brokerage firm. Wikipedia says "At the time of the September 11 attacks in the United States in 2001, the corporation held offices on eight floors of the North Tower of the World Trade Center, from 93 to 100. When American Airlines Flight 11 crashed into the building, their offices spanned the entire impact zone, from floors 93 to 99. No one present in the offices at the time survived the attack, and the firm lost 295 employees and 63 contractors." Their London HQ is at Tower Bridge House on St Katharine's Way.