I'd like to understand, how should I interpret the VFIAX mutual fund historic prices, which can be found @ Google Finance and @ Yahoo!Finance. For example, both these sites show the VFIAX closing price $428.91 on 12/21/2021. However when I look at my account history @ Vanguard, I see that I've purchased a piece of this fund @ $421.39 on this date.
Why this discrepancy? Is some price adjustment involved here? If yes, then how they calculate the adjusted price?