The squeeze instigated by a group of traders on Gamestop has now spread to other heavily shorted stocks,
There was no news out on any of these three stocks today, and certainly nothing of the kind that would generate this kind of movement for fundamental reasons.
Instead, traders on platforms like Reddit have figured out that they can take advantage of heavily shorted small-cap stocks if enough of them start buying them, and that's what's happened with all three of these stocks. When a stock is shorted and starts to go up, short-sellers eventually have to buy back the shares or risk further losses, including a margin call forcing the repurchase.
Though only about 15% of the float is sold short, traders were aggressive to pump up the stock as daily trading rose as high as 358 million shares on Monday, up from around 3 million normally. As of midday today, had already topped 200 million.
PetMed Express, an online pet pharmacy, entered the new year with 41% of it stock sold short.