A Russian businessman and Kremlin insider suspected of insider trading appeared in US court Monday after being extradited from Switzerland over the weekend.

The United States has accused Vladislav Klyushin, 41, of insider trading to the tune of tens of millions of dollars, alongside several accomplices. The other suspects are still on the run.

According to Russian opposition media reports, Klyushin is very close to senior Kremlin official Alexei Gromov.

Klyushin and his accomplices are accused of hacking into listed American companies and obtaining unpublished quarterly results presentations.

The group then conducted stock market transactions in anticipation of the market's reaction to the announcement of the results.

In total, through more than 500 earnings presentations obtained between 2018 and 2020, the hackers made at least $82 million in illegal profits, according to the Securities and Exchange Commission, the US market regulator.

Klyushin appeared before a federal judge in Boston on Monday. He had been handed over to US authorities on Saturday.

A Swiss federal court approved the extradition in a judgment dated November 16. Klyushin's appeal, which argued he was being politically targeted, was rejected.

Charged with criminal conspiracy, unauthorized access to computers, fraudulent financial transfer and stock market fraud, he faces several decades in prison.

The last two counts are each punishable by a maximum of 20 years behind bars.

Klyushin was arrested in the Swiss canton of Valais in March.

He reportedly heads several companies, including the M13 group which specializes in IT solutions for media monitoring and cyber-security consulting.

The "Katyusha" media-monitoring system the group developed has been used by the Russian presidency since 2016 and several other ministries.