<prompt> Human: When I first started investing, I put a fair amount of money into mutual funds because I didnt know any better. Ive since learned about index funds and thats where Ive been investing the lions share of my money for the past 5 years or so. Although I do own a few individual stocks. This is my question. Does it make sense for me to look into selling my mutual funds and reinvest in index funds? Obviously, I will have to pay some sort of commission when I sell the mutual fund and then buy the index, but I guess I need to look at the fees the mutual fund charges over the next X years vs. the immediate transaction costs today? Also, I guess Ill have to pay tax on the money made from the mutual fund sale?Im not going to do this immediately, and I know everyones situation is different, but Im just asking the question to get a macro perspective of what I should do. Here are more details that may factor into the answer to my question. Im 36 years old, no debt, in better financial shape than most my age, relatively high income, and I dont plan on touching the money for a long time. US resident. The mutual funds are with fidelity. Id estimate they are worth about 50K.  <response>: index funds are mutual funds. yes, it can be a good idea to move from actively managed mutual funds to index funds...typically index funds are more diverse and have lower expense ratios. 