The idea is that just as you&#x27;re supposed to want to lend... you might also choose to stockpile cash. Both strategies potentially mitigate the negative interest. In tho regime, banks pay the central banks less in the future for money they take on loan now. The common sense assumption is that this means money will be worth more in the future. Therefore you may want to invest in cash. At a point, this makes cash like gold traditionally and hence stockpiling aka fort Knox. But that&#x27;s why you can go negative...you just cant go negative enough such that folks start stockpiling. Iraw expensive to stockpile