U.S. stocks may have gotten a jolt with Great Britain's decision to leave the European Union, but they remain in a 'sideways' market nonetheless, said Craig Ferrantino, president of Craig James Financial Services. 'We saw a nice run up into the Brexit decision and now the market is giving it all back,' said Ferrantino. He added that investors never seem to panic when there is volatility on the positive side, yet when they encounter volatility on the negative side they 'get frozen and want to do something, and usually they do something detrimental to their portfolios.' Ferrantino said a sideways market impacts impatient investors the most. In his view, the longer the sideways market continues, the more likely an impatient investor will switch to another asset, perhaps losing out on possible upside when the direction becomes clear. 'Research shows most individual investor losses come from selling at the wrong time and investing at the wrong time,' said Ferrantino. Outside of impatient investors, retirees greatly feel the effects of a sideways market. Volatility is terrible for a retiree, especially if they are taking money from their portfolio or taking out their required minimum distributions, according to Ferrantino.