The Asset Correlation of the 2 funds is .92 via portfolio visualizer. So they are 92% similar. I prefer index funds for the low fees and am very comfortable with the total market index fund. You did not say if the investment was in a Tax deferred or Brokerage account. If it was in Tax-deferred, I would switch it all to the index fund. If it is in brokerage, it is not worth the capital gains to switch, leave it alone and put any additional funds into the index fund.