Tossing a coin

If your time horizon while investing in the stock market was only one day, the probability of a loss in US equities was statistically 46% over the last 100 years. This is almost the same probability than tossing a coin and a random choice between a gain and a loss. If your investment horizon increased to 5 years, the probability of negative returns dropped to 10%. In other words, investors have in the past been 90% sure not to lose any money if they invested in the S&P 500 over 5 years.