<prompt> Human: I have seen many posts advocating for Vanguard and Im curious to know why. My 401K is through Fidelity. Can someone give me some perspective? Thanks.  <response>: Vanguard, Fidelity and Schwab are all excellent and popular choices, each with a selection of good low-cost funds.Vanguard is popular with many because John Bogle, their founder, popularized index funds, and because Vanguard is a mutual company owned by its funds, so if you buy into their funds youre a part owner of the company. 