Naked shorting is the illegal practice of short selling shares that have not been affirmatively determined to exist. Ordinarily, traders must borrow a stock, or determine that it can be borrowed, before they sell it short. So naked shorting refers to short pressure on a stock that may be larger than the tradable shares in the market. Despite being made illegal after the 2008-09 financial crisis, naked shorting continues to happen because of loopholes in rules and discrepancies between paper and electronic trading systems.