Image copyright Reuters Image caption Martoma was stony-faced as he left court after the guilty verdict

A former manager at SAC Capital, a major US hedge fund founded by billionaire Steven Cohen, has been found guilty of insider trading.

Mathew Martoma was found guilty of conspiracy and securities fraud for his part in a scheme that made SAC $275m (£169m) in profits and avoided losses.

Prosecutors in New York called it the most lucrative insider trading scheme in history.

SAC paid out a total of $1.8bn last year to settle related charges.

Mr Cohen, who founded SAC in 1992, has not himself been charged with any wrongdoing.

But he faces civil action from US regulators who say he failed to supervise Martoma and a fellow trader properly, allowing them to conduct insider deals. He disputes the allegations.

Alzheimer's drug scam

Prosecutors outlined how Martoma cultivated relationships with doctors involved in the trials of a new Alzheimer's drug.

Two doctors confessed to telling him the results of the trials in advance, allowing SAC to "short" the stocks of the two research companies involved.

This delivered massive profits when the share price fell on the publication of the trial data, and earned Martoma himself a $9m bonus.

The conviction is being seen as yet another success for New York federal prosecutors, who have secured a total of 79 guilty pleas or verdicts relating to insider trading since 2009.

Martoma's conviction is the eighth involving current or former employees of SAC, which was once an unrivalled hedge fund presence on Wall Street.

His lawyers said he planned to appeal against the conviction, which could see him face up to 45 years in prison.