William Dean Chapman, 44, of Sterling, Va., was sentenced to 12 years in prison Friday after pleading guilty to one count of wire fraud in May, the U.S. attorney's office in Alexandria said.
Politico said Chapman was the founder and owner of Alexander Capital Markets, in which clients would give their stock holdings to Chapman as collateral for loans. Officials said Chapman sold the stocks, despite assuring the customers that they would get back the full value of their holdings.
An unnamed official named "A.G." in court documents was identified as having lost more than $18 million around 2007 in the scheme.
After Chapman unsuccessfully tried to withdraw his guilty plea at the last minute, prosecutors submitted a document publicly naming Grayson as "A.G." to head him off, Politico said.
A Grayson aide confirmed the victim was the congressman, the newspaper said. Grayson built his fortune by helping to create a long-distance telecommunications company.