Brokers Cantor Fitzgerald lost 658 staff in 9/11
9 September 2011 Last updated at 15:08 BST
On 11 September 2001, brokers Cantor Fitzgerald lost three out of every four people based in its New York Office.
The 658 staff who died, including 63 British people, were working on the 101st to 105th floors of the North Tower: that was just above where the hijacked American Airlines flight 11 crashed into the building.
More people died from the company than from any other organisation, including the Fire Department of the City of New York.
In 2004, Cantor Fitzergerald became BGC Partners.
David Buik, from the firm, told Radio 5 live Wake Up To Money what he remembered most about 9/11.
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There are more details of 5 live's coverage of the 10th anniversary of 9/11 on the 5 live blog.