The biggest home mortgage lender in the U.S., Rocket (NYSE: RKT) joins a group of stocks that have recently received massive boosts from retail traders, like those from Reddit’s WallStreetBets forum, who’ve piled into heavily shorted stocks. Shares of Rocket, the parent company of Quicken Loans, closed up 71.2% at $41.60 after being halted several times for volatility. More than 367 million shares changed hands in the stock's busiest trading day ever.