Perhaps the only certain thing in investing is that index funds will continue to take the lion's share of new investment capital coming into the stock market. From 2009 to July 2016, passive index funds grew in every single year as investors added more money to low-cost funds. Meanwhile, active funds have experienced outflows as investors pull money from higher-fee funds and the pace of redemptions is accelerating.In this clip from Industry Focus: Financials, The Motley Fool's Gaby Lapera and Jordan Wathen discuss everything you need to know about investing in index funds, why they're so popular, and why they may be a great investment for your retirement portfolio.A full transcript follows the video.Continue reading