谁能解释为啥有人买负利率bond？法国德国政府今年都发过负利率bond，好像都卖了。为啥？搞不懂！

https://www.reuters.com/article/us-germany-bonds-centralbanks-analysis/who-is-buying-negative-yielding-german-bonds-foreign-central-banks-perhaps-idUSKBN1WX0JN