A federal jury in Los Angeles has convicted an activist short seller of securities fraud for a long-running market manipulation scheme that reaped more than $21 million in profits.

According to court documents and evidence presented at trial, Andrew Left, 55, of Boca Raton, Florida, was a securities analyst, trader, and frequent guest commentator on cable news channels who manipulated the prices of publicly traded securities to profit from investors who trusted him.

As part of his scheme, Mr Left made false and misleading statements—in the form of online posts and public reports—about publicly traded companies, asserting that the market was misvaluing a company’s stock and advocating that the current price was either too high or too low.

Mr Left knowingly exploited his ability to move stock prices by targeting popular stocks with retail investors and posting recommendations on social media to manipulate the market and make quick, easy money.

In anticipation of his public commentary, Mr Left established long or short positions in the public company on which he was commenting and prepared to quickly close those positions post-publication and take profits on the short-term price movement caused by his commentary.

In advance of his tweets and reports, Mr Left would enter limit orders to trade in the opposite direction of his public recommendations.

Furthermore, Mr Left used his advance knowledge and control over the timing of a market-moving event to build his positions using inexpensive, short-dated options contracts that expired on the same day he published his commentary, or within five days thereafter.

To further the scheme, Mr Left advanced the false pretence that his investment recommendations were credible because he was independent and free from any financial conflicts of interest.

Mr Left was convicted of one count of participating in a securities fraud scheme and 12 counts of securities fraud. He is scheduled to be sentenced on August 31. He faces a maximum penalty of 25 years in prison.

A federal district court judge will determine any sentence after considering the U.S. Sentencing Guidelines and other statutory factors.