I have some Vanguard accounts that contain investments in their Small Cap Value Index Fund Admiral Shares (VSIAX). I think it started some months ago, but continues every day. In the evenings, after market close, my "Market Value as of Today" amount adjusts to reflect the closing values of the day. The next morning, every single day, my VSIAX funds drop in value by at least a percentage point, often more, which shows my overall market value balances for the day to be in the negative for the whole day. These are the only index funds that I own that show any kind of change before market close. Then, again, after market close, the real value is reflected and the massive losses from nowhere are replaced with the day's real gains or losses. Why do these funds start the day as if they've lost a lot of value, even if they just gained value the night before?