非退休賬號下,不僅可選first,last，還可以選任何日買進的賣,可以根據你自己保稅情況決定。tax loss har

Tax-loss harvesting is a way to cut your tax bill by selling investments at a loss in order to deduct those losses on your taxes. Deducting those losses can offset some or all of the capital gains tax you might owe on other investments that you sold for a profit