https://grafioschtrader.github.io/gt-user-manual/en/reportportfolio/costbasismethod/index.htmlAnyone who bought a security in several tranches at different prices and sells only part of it has to decide which purchases this sale consumes. This determines the cost of the sale and therefore its gain, and which cost remains for the holding that is left. In GT this decision is called the Cost basis method. It is chosen for the client and can be overridden for a single portfolio. Note The method moves gain between realized and unrealized, it does not change the total gain. Whatever a sale shows as additional gain, the remaining holding shows less. The Gain security of a position, its Forex gain, its value and the assets are therefore the same with every method.Hugoen