Day traders continued to take on Wall Street investors, pumping stocks traditional investors have been shorting.

GameStop made headlines when its stock surged after Citron Research’s Andrew Left urged investors to short it. Traders took to Reddit to urge others to buy, causing the stock to hit as high as $247 in after hours trading Tuesday, a far cry from the $18 it was at a couple of weeks ago.

GameStop isn’t the only company to see its stock take off. AMC has risen some 310%, Blackberry 24% and Bed Bath & Beyond 46%, according to Business Insider. It appears that day traders are engaging in a new level of activism, targeting stocks that institutional investors are shorting. The end result is volatile trading that has caused traditional investors to suffer heavy losses.

The situation is not going unnoticed, with WH Press Secretary Jen Psaki saying the White House and Treasury Department were monitoring the situation.