<prompt> Human: Back when I was a teenager, my dad helped me invest 3,000 in two mutual funds that have since grown to a total of 17,000. In the 20 years Ive had the account, I havent added to or withdrawn from it. The expense ratios are 1.1 and 1.35.Comparing those to Vangaurds much smaller ratios of 0.05, 0.15, and 0.2 obviously rocking a lazy portfolio here, selling should be no-brainer. I have my reserves about selling because Id have to pay taxes on it. If this were common stock, I wouldnt bat an eye. However, selling a diversified mid-cap mutual fund just to put it into diversified mid-cap index fund seems like a waste of 2100 the capital gains tax.Can someone poke some holes in my line of thought here?  <response>: Well, you need to make some assumptions... some of which may not be true, but as a rough example you can compare the two strategies accounting for the capital gains tax and an expected return minus the annual expense of owning the different funds. Example 1: 17,000 initial investment what you have now, 30 years, 8 return minus 1.2 expense rough average 6.8 return. End value before tax: 122,345.08 Example 2: 14,900 initial investment Original 3k plus 14k gains minus 15 capital gains tax, 30 years, 8 return minus 0.2 expense 7.8 return. End value before tax: 141,823.79Obviously you can change any of the variables to get a different answer, but if you adjust the number of years invested the index fund pulls ahead in year 13. In my opinion youd be hard pressed to justify sticking with the expensive funds if youre in it for the long term. 