Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

U.S. Mutual Fund Supermarkets: Where are some good places to buy mutual funds?
There are hundreds of entities which offer mutual funds - too many to adequately address here. If you need to pick one, just go with Vanguard for the low low low fees. Yes, this is important. A typical expense ratio of 1% may not sound like much until you realize that the annualized real rate of return on the stock market - after inflation - is about 4%... so the fund eats a quarter of your earnings. (Vanguard's typical expense ratios are closer to 0.1-0.2%). If your company offers a tax-deferred retirement account such as a 401(k), you'll probably find it advantageous to use whatever funds that plan offers just to get the tax advantage, and roll over the account to a cheaper provider when you change employers. You can also buy mutual funds and exchange-traded funds (ETFs) through most brokerages. E*Trade has a nice mutual fund screener, with over 6700 mutual funds and 1180 ETFs. Charles Schwab has one you can browse without even having an account.