Unlike most online stock trading platforms, Robinhood doesn’t charge a commission fee every time you buy or sell stocks, ETFs, or options. If you’re a high-volume trader, or a beginner without much cash to spare, that makes Robinhood an attractive alternative to the $5 to $7 fees per trade offered by competitors. However, Robinhood does rake in “payment for order flow” by rounding regulatory fees up to the nearest penny and pocketing the difference. “That means if you buy a stock for $100.00, Robinhood earns 2.6 cents from the market maker,” says co-founder and co-CEO Vlad Tenev, whereas “other brokerages earn rebates and charge you a per-trade commission fee.”
According to one interpretation of the efficient-market hypothesis (EMH), only changes in fundamental factors, such as the outlook for margins, profits or dividends, ought to affect share prices beyond the short term, where random 'noise' in the system may prevail. The 'hard' efficient-market hypothesis does not explain the cause of events such as the crash in 1987, when the Dow Jones Industrial Average plummeted 22.6 percent—the largest-ever one-day fall in the United States.