BDO USA

BDO USA, P.C. is the 8th largest accounting and professional services firm in the United States by revenue. It is the United States member firm of BDO International.

In 2023, BDO USA, P.C. took a loan of $1.3 billion from Apollo Global Management in order to convert from a traditional limited liability partnership to an employee owned corporation. The majority of the borrowed amount was distributed to senior equity owners of BDO USA in exchange for their partnership units. This conversion is currently the subject of a class action lawsuit against BDO USA, P.C., its board of directors, and the ESOP trustees.

The company is currently headquartered in downtown Chicago. BDO stands for Binder, Dijker, and Otte, the original founders of the firm.

BDO USA, P.C was founded as Seidman and Seidman in New York City in 1910 by three immigrant brothers: Maximillian L. Seidman, Francis E. Seidman, and Jacob S. Seidman. At that time the accounting profession was in its infancy, with fewer than 2,200 practicing CPAs in the United States. Shortly thereafter in 1913, the Sixteenth Amendment to the United States Constitution was ratified, followed by the Revenue Act of 1913 with new impositions of U.S. federal income tax enacted by Congress in that year. M. L. Seidman saw the potential of the accountant's role to provide tax services to individuals. By 1917, Congress enacted the first revenue bills and the U.S. entry into World War I created the need for corporate income and excess profit taxes. At the same time, federal spending rose to $18.9 billion, with 58 percent of federal revenues provided by income taxes. M.L. Seidman and his siblings, who joined him in his new accounting firm, seized the opportunity to provide tax services to businesses in addition to individuals.

An era of expansion began. Fostered by the federal government's conversion of furniture and woodworking companies to aircraft production for the war effort, the firm opened an office in Grand Rapids, Michigan, in 1917. Seidman and Seidman quickly established itself as a leader in serving the furniture industry by developing the first effective furniture plant costing system. Today, BDO Seidman's furniture industry practice remains in use in the industry.^{[citation needed]}

In 1925, the firm rapidly expanded, opening offices in Jamestown, Illinois, and Rockford, Illinois, followed by Chicago in 1921, and Gardner, Massachusetts, in 1924. In 1922, J. S. Seidman joined the firm as a founding member.

The 1930s brought another new beginning for the accounting profession. In 1933, Congress passed the Securities Act, requiring public corporations to have financial statements included in registration statements and periodic reports reported on by independent CPAs. A year later, the Securities and Exchange Commission was created to administer the new legislation.

In 1950, L. William Seidman joined the firm and ultimately became its managing partner before leaving for government service, most notably as chair of the FDIC.