Let's say, completely hypothetically, that I own 1,000,000 shares in Company X, and their share price is exactly $10.00. Theoretically, this is worth $10 million, but obviously if I wanted to liquidate this quickly and I placed an order saying "sell 1,000,000 shares at market," it would drive the price down and I'd end up getting significantly less than $10 million out of it.
Is there any accepted way to calculate (a reasonable approximation of) how much this sale would actually be worth? I figure it would probably have to take into account factors such as current trading volume on Company X and the total number of shares outstanding, but I don't know enough to know what I don't know...