ExxonMobil the Exxon Building (1251 Avenue of the Americas), its former headquarters in Rockefeller Center, to a unit of Mitsui Real Estate Development Co. Ltd. in 1986 for $610 million, and in 1989, moved its headquarters from Manhattan, New York City to the Las Colinas area of Irving, Texas. John Walsh, president of Exxon subsidiary Friendswood Development Company, stated that Exxon left New York because the costs were too high. On March 24, 1989, the Exxon Valdez oil tanker struck Bligh Reef in Prince William Sound, Alaska and spilled more than of crude oil. The Exxon Valdez oil spill was the
Oil tanker instrument, Shell consulted the "London Tanker Brokers’ Panel (LTBP)". At first, they divided the groups as "General Purpose" for tankers under ; "Medium Range" for ships between 25,000 and and "Large Range" for the then-enormous ships that were larger than . The ships became larger during the 1970s, which prompted rescaling. The system was developed for tax reasons as the tax authorities wanted evidence that the internal billing records were correct. Before the New York Mercantile Exchange started trading crude oil futures in 1983, it was difficult to determine the exact price of oil, which could change with every contract.