Over the past week, the popular stock trading app Robinhood has drawn the ire of the internet as it restricted trades of GameStop, AMC and other wildly swinging stocks. The move interrupted, for a short time, a showdown between Reddit users and large investors that's become one of the biggest dramas in Wall Street history. Now the Securities and Exchange Commission says it will "closely review" what happened.

In a statement Friday, the acting chair of the SEC and three commissioners said the commission is "closely monitoring and evaluating the extreme price volatility of certain stocks' trading prices over the past several days." 

The statement didn't mention Robinhood by name, but the commission said it would "closely review actions taken by regulated entities that may disadvantage investors or otherwise unduly inhibit their ability to trade certain securities." 

Robinhood declined to comment about the SEC statement. The White House referred questions about GameStop and brokerage firms to the Treasury Department, which houses the SEC.

The announcement comes amid increased calls among internet traders for government regulators to closely scrutinize Wall Street trading apps, including Robinhood. Critics say Robinhood, whose motto is to "democratize finance for all," acted dishonestly and may have manipulated markets when it appeared to halt purchases for GameStop and other stocks on Thursday. Robinhood at the time said its restrictions were to ensure it didn't run afoul of government regulations.

All this happened in the midst of a pitched battle between traders on the Reddit forum r/WallStreetBets and large Wall Street investors. The Wall Street investors had made big bets against GameStop's and AMC's success, which turned sour when large numbers of WallStreetBets members invested in GameStop. As GameStop share prices soared, Wall Street investor losses rose into the billions, driving even more share trading.

As trading volume for the various stocks has risen, stock market trading app brokerages have restricted trades by adding extra account requirements, among other things. Some investors have accused brokerages and app makers of attempting to manipulate the market, but the companies say they're ensuring their firms work smoothly.

Meanwhile, Robinhood announced it had raised $1 billion from its existing investors, "to invest in record growth." Though some media reports say Robinhood has drawn down on its credit as well to help stabilize its business amid the havoc.

The SEC's investigation may ultimately help to more directly identify the brokerage's behavior.

"Our core market infrastructure has proven resilient under the weight of this week's extraordinary trading volumes," the commission added in its statement. "Nevertheless, extreme stock price volatility has the potential to expose investors to rapid and severe losses and undermine market confidence."