An Amazon Marketplace merchant was charged under federal antitrust law for colluding with other sellers to fix the prices of wall posters. Amazon.com Inc. was not charged in the investigation. Reuters

An Amazon Marketplace seller is being prosecuted for price-fixing in what the U.S. Department of Justice called the first prosecution to target e-Commerce on Monday. David Topkins was charged under federal antitrust law for fixing the prices of posters online with a number of other sellers.

Topkins pled guilty to conspiring to fix the prices of posters sold on the Amazon Marketplace -- the online retail giant’s own eBay-competitor -- from September 2013 to last January, according to Reuters. He allegedly built a custom software to determine price changes based on which posters were popular, and determined price changes that he shared with other Marketplace sellers.

Topkins will avoid a maximum 10-year prison term and $1 million fine if his deal is approved. Topkins shared information about sales to determine prices among a number of other vendors to fix prices, violating the Sherman Act, according to the Justice Department. The federal antitrust law prevents the merchants colluding to sell items at “non-competitive” rates.

"We will not tolerate anticompetitive conduct, whether it occurs in a smoke-filled room or over the Internet using complex pricing algorithms," Bill Baer, assistant district attorney for the Justice Department's antitrust unit, said in a press release. "American consumers have the right to a free and fair marketplace online, as well as in brick and mortar businesses."

The Amazon Marketplace competes with eBay Inc. by allowing third-party sellers to offer goods on Amazon’s site for a fee. It is separate from Amazon’s regular business, where the company directly sells goods to consumers. The Seattle, Washington-based e-commerce giant was not charged in the price-fixing scheme.