Advanced Automatic Investor

[glennpj]

I think what Aimster was referring to was a recalculation of the average cost of the shares remaining after a sale. This has nothing to do with the proceeds of the sale, only the cost of previously purchased shares. For example, if one buys 10 shares for $10 and the next month buys 10 shares for $9, the average cost of the shares is $9.50. If the next month the 10 shares of the initial tax lot are sold (sale price is irrelevant), the average cost of the remaining shares is actually $9, not $9.50, because all of the remaining shares are from the $9 tax lot.