Shares of Chewy popped in the premarket trading Monday after a Securities and Exchange Commission filing showed meme stock trader "Roaring Kitty" took a stake in the pet food e-commerce retailer. The filing showed Keith Gill bought just over 9 million shares — amounting to a 6.6% stake in the company. That makes him the third-biggest Chewy shareholder, according to FactSet. Based on Friday's close, that stake is valued at more than $245 million. The stock was up more than 20% before the bell. ...