Based in Chicago with an international reach

Grant Thornton LLP is the U.S. member firm of Grant Thornton International, Ltd. Grant Thornton's service lines are divided into audit, tax, and advisory services. In regards to industry, it fields practices in consumer and industrial products; technology; financial services and institutions; not-for-profit; construction, real estate, and hospitality; global public sector (including local, state, federal, and international governments); health care; and private equity. 

Alexander Richardson Grant, the namesake of the firm, began his accounting career at Ernst & Ernst (a predecessor of Ernst & Young) but, at the tender age of 26, decided it was time to be his own boss. Alexander Grant & Co. opened in Chicago in 1924 with a mission to provide accounting services to middle-market companies. Grant died suddenly in 1938, but his firm continued to grow. By 1961, net revenue exceeded $5 million, and in the late 1960s, Alexander Grant & Co. joined with firms in Australia, Canada, and the U.K. to establish Alexander Grant Tansley Witt, which operated internationally for 10 years. Grant Thornton International was born in 1980 when Grant and 49 other international accounting firms formed a global organization; by 1985, Alexander Grant & Co. was ranked the ninth-largest accounting firm in the U.S. It changed its name to Grant Thornton in 1986, a reflection of its affiliation with the U.K. firm Thornton Baker (which also changed its name). 

Today, Grant Thornton LLP employs more than 6,200 people and is the sixth-largest accounting firm in the U.S., according to Accounting Today's latest rankings by revenue.