Reddit Inc. is weighing feedback from early meetings with potential investors in its initial public offering that it should consider a valuation of at least $5 billion, according to people familiar with the matter, even as it is estimated below that figure in the volatile market for shares of private companies.
shorting means to bet against a stock. instead of buying a stock and waiting for it to grow over a long period and selling it for more money (long position), you borrow the stock from somebody, sell it, then buy it back (for a lower price) after a short amount of time to give back to whom you borrowed it from. (short position). If the stock price rapidly drops in that time, you gain money.
If this sounds like a perversion of what investing was supposed to be, yeah welcome to wall street