Philip Kueber, 54, pleaded guilty in federal court in Brooklyn to charges he conspired to commit securities fraud and money laundering.

He was the first of nine defendants to admit wrongdoing in connection with the scheme.

"I knew what we did was against the law, and I accept responsibility for my actions," he said at a hearing.

Kueber also agreed to forfeit $1.2 million as part of a plea agreement. He will be sentenced on Jan. 7, 2016.

His lawyer, Stanley Greenberg, declined to comment after the hearing.

U.S. regulators in July 2014 suspended trading in Cynk, a social media company with no revenue or assets, after its share price soared without explanation to $21.95 from 6 cents in less than a month.

That surge followed a month when no Cynk shares were traded at all, and briefly gave the company a market value higher than three dozen companies in the Standard & Poor's 500.

Kueber, who authorities say has also lived in California and Belize, a Central American country, surrendered in August. His surrender came a month after being indicted over his alleged role in a scheme run by a group controlled by Gregg Mulholland, a U.S.-Canadian citizen arrested in June.

Both men were added as defendants to a case involving the alleged operators of Belize-based IPC Corporate Services, which authorities said helped clients evade U.S. securities laws.

Mulholland and Robert Bandfield, the accused founder of IPC, are being held without bail. The six other defendants have not appeared in U.S. court.

The case is U.S. v. Bandfield, U.S. District Court, Eastern District of New York, No. 14-00476.

(Reporting by Nate Raymond in New York; Editing by Chizu Nomiyama and Jonathan Oatis)