The investment liquidation and purchase adjustment method is an investment model for open-ended investments that takes into account the net asset value (NAV) of the mutual fund and an accumulated stock brokerage transaction commission fees. The accumulated commission fees are added to the net asset value per share prior to the purchase of shares of the mutual fund. Alternatively, the accumulated commission fees are subtracted from the net asset value per share prior to the liquidation of the shares. These additional fees flow into the assets of the mutual fund. As accumulated brokerage transaction commissions change each day because of the trading of the positions in the mutual fund, the brokerage transaction commission's percentage change on a daily basis, too. This also solves the problem of maintaining the true asset value for existing shareholders when there are share liquidations by existing shareholders, protecting the true asset value for the remaining existing shareholders.