The firm traces its founding back to 1848 , when Benjamin Franklin Butler opened a legal practice with his son , William Allen Butler , at 29 Wall Street in New York City . The firm was headquartered in downtown Manhattan from 1848 until 2001 , eventually occupying floors 38 through 40 of the 2 World Trade Center building prior to the building 's destruction in the September 11 attacks . All of the firm 's employees survived the attacks , and the firm temporarily relocated to midtown Manhattan before moving to 2 World Financial Center in September 2003 . Thacher Proffitt was a market leader in the mortgage-backed securities ( MBS ) market , and in fact was instrumental in the creation of the residential MBS and commercial MBS markets . The firm so controlled the market that the standard documentation used by mortgage traders was known as " Thacher docs " and " TP&W forms . " The firm grew from 177 lawyers in 2003 to 350 lawyers in 2007 , mostly due to the strength of its structured finance practice , which came to constitute 70 % of the firm 's revenue . The firm also had highly regarded real estate , litigation , corporate , tax and derivatives practices . In 2006 , the firm was ranked among the top 200 by '' The American Lawyer '' . It was also ranked among the top 80 most prestigious law firms in the nation by Vault
September 11 attacks
September 11 attacks
Thacher Proffitt & Wood