Some brouhaha around this in Denmark:
Jyske Realkredit is ready with a fixed-rate mortgage with a nominal interest rate of minus 0.5%.
Yes, you read right. You can now get a fixed-rate mortgage with a maturity of up to 10 years, where the nominal interest rate is negative. However, you are not exactly going to make money borrowing. Namely, there must also be paid, among other things, establishment fees and contributions, and there will be a loss of prices.