Interest rates are always positive. You are referring to yields which are part interest rate and part trading issues. Yields can and do go negtaive from time to time from the trading issues around the products. The interest rate (as shown on the coupon payment on the bond) will always be positive.
edit: let me add, I mean the consumer space. There can be some oddity in the bank-to-bank market because of various technical reasons, but it is extremely rare.
There are mortgages in Europe which are indexed to Euribors, which have been negative for a while, and you have been able to end up having a mortgage where index + margin is below zero. Obviously banks argue that actually mathematics is wrong and negative numbers do not exist, so customer needs to pay more than what was originally agreed, and I am not sure if that issue has been sorted out in courts.
What comes to interbank markets, it is far from rare and far from only technicalities, it is nowadays pretty normal that the floating leg of the swap pays negative interest rate. (In Euro, that is, USD has higher rates)
Euribor rates are just short end bank-to-bank reference pts. The interbank markets are mostly technically driven on the short end. Central bank policies (eg reserve requirements) play the largest role.
And can you show me euribor-based long-term loan where the interest rate is negative? For the most part, banks have no need to loan unless compelled, so maybe where is some policy forcing them to? I would call those extremely strange technical factors.
> And can you show me euribor-based longe-term loan where the interest rate is negative?
My old mortgage would have become technically negative a couple of years ago, but I was forced to prepay it due to selling my apartment before the rates went that far down. As I said, my understanding is that my bank would have refused to honor our contract, though, and insist there is a zero floor in my mortgage even if nothing like that was agreed when I took the loan, so in that sense you are right.
> The interest rate (as shown on the coupon payment on the bond) will always be positive.
Negative coupons would be quite difficult to implement but having a positive coupon doesn't really mean anything: bonds are not necessarily sold at the nominal price even when they are initially issued.
"Henkel and Sanofi sell first negative yielding euro corporate bonds"
edit: let me add, I mean the consumer space. There can be some oddity in the bank-to-bank market because of various technical reasons, but it is extremely rare.