CNBC’s Bob Pisani spoke with Dan Egan, managing director of behavioral finance and investing at Betterment, and John Davi, founder and chief investment officer of Astoria Portfolio Advisors. They discussed retail investors’ rush to the stock market, social media, and their top picks for the second half of 2020. In the 'Markets 102' section, Bob discusses the different types of ETF trades and how they generate returns.