Low interest rates for a long time are tough for banks. A study looked at 3,385 banks in 47 countries from 2005 to 2013. They found that when interest rates drop by 1%, banks make 8 basis points less money. This effect is worse when rates are already low, with a 20 basis point drop. Low rates also hurt bank profits, but the impact varies. Every extra year of low rates makes banks lose 9 basis points in profit and 6 basis points in margins.