Does anybody know how websites like Personal Capital and SigFig track the performance of your investments? For one thing, in both SigFig and Personal Capital, their performance trackers never seem to factor the change in my 401k, which is entirely in an S&P500 mutual fund. It only seems to accurately capture the ETFs in my IRA. The account updates in terms of total amount, but the performance of my portfolio always seems to lag the market (when the market does well) and beat the market (when the market does poorly) and it appears to be directly related to my S&P500 mutual fund. I'm not sure if this has to do with the fact the fact that it's a mutual fund, or it's part of my 401k, or what.
Additionally, how do these performance trackers factor in the fact that I'm DSAing? They don't seem to be able to show how much my portfolio has grown due to the market, as opposed to the fact that I'm buying more shares.
Also, in Personal Capital, what's the difference between the "You Index" and the "Performance" tab? For example, in the past 6 months, my "You Index" is +6.74% whereas my holdings are +46.48%.
And on another note, why is Mint.com's investment tracker atrociously inaccurate? I can't make any sense of it.