<prompt> Human: Hey PF...question that I cant seem to wrap my head around. My primary investments are in IVV, an SP tracking ETF. Yesterday, the fund returned -0.04 where to SP returned 0.31 I know its not significant, but usually it tends to move in lockstep with each other.Any insight would be appreciated.  <response>: See NAV vs. Price.If you are going to invest in ETFs, you need to understand the concept of discount or premium to NAV. It is currently at a discount to NAV.Usually liquid and popular ETFs will correct quickly 