The network was alleged by the Securities & Exchange Commission to have fraudulently misstated its financial results from 1997 to 2004 by failing to account for inter-company transactions properly, leading Interpublic to restate its financial results.
McCann Erickson and Interpublic neither admitted nor denied wrongdoing in the settlement but did agree to refrain from future violations of the securities laws.
The SEC also filed a complaint against Salvatore LaGreca, a former chief financial officer of McCann Erickson, and Brian Watson, a former director of operations in its Europe, Middle East and Africa region.
LaGreca agreed to pay a $25,000 fine and $46,947 in reparation, while Watson agreed to pay a $50,000 fine and reparation of $17,325. Neither admitted nor denied the SEC's accusations.
The accounting troubles have caused chaos at Interpublic for several years since the regulator's investigation began in 2002.
In 2002, Interpublic restated its earnings by $181m for 1997 to 2002, the SEC said.
In September 2005, Interpublic again restated its pre-tax income for the years 2000 to 2003 and the first nine months of 2004 in the amount of $420m.
Michael Roth, Interpublic's chairman and chief executive, said: "We are very pleased to have settled with the SEC and we believe this matter is now behind us.
"Under current management, we have devoted considerable resources to replacing and expanding staff in the relevant areas and our efforts to remediate material financial control weaknesses and improve financial reporting have been a top corporate priority for all of our agencies."
Yesterday, Interpublic reported a first-quarter loss of $62.8m, and revenues of $1.5bn.
The figures are an improvement on the same quarter last year, when IPG lost more than $125m and reported revenues of $1.36bn.