The US Department of Justice and the San Francisco State Attorney are looking at whether the price hike of GameStop and AMC shares was subject to price manipulation a few weeks ago.
The American business newspaper The Wall Street Journal writes this on the basis of insiders.
Three weeks ago, the price of the computer games seller GameStop and the cinema chain AMC exploded after some investors on the discussion forum called on Reddit to buy the shares en masse.
They wanted to put so-called shorters, who profit from a price reduction, a heel.
As a result, GameStop's share went more than 2,000 percent higher in two weeks to 483 dollars (398 euros).
See also: Small investors get rich at the expense of hedge funds with GameStop
Meanwhile, things seem to have settled down and a share of GameStop will cost only about 50 euros, but the authorities have opened an investigation.
They suspect the Reddit traders of price manipulation by promoting the stock on the forum.
They also look at whether other forms of misconduct have been committed.
They requested data from, among other things, the investment app Robinhood, which many small investors are active on.
Subsequently, the commodities authority is also investigating whether investors have gone over the line when they sent the silver price up a little later.
See also: After GameStop, smaller investors are now targeting silver
Earlier it became known that the stock market watchdog SEC had launched an investigation into the event.
There will be a hearing in the US House of Representatives next Thursday to find out what exactly happened.
The Dutch watchdog AFM also launched an investigation into the way in which brokers BinckBank and DeGiro have dealt with the madness.
See also: AFM investigates brokers with GameStop shares