 the 2017 stress test. We the ECB supervisors conducted this stress test because we wanted to know how banks would hold up if interest rates changed if hypothetical shocks were applied. It's called IRBB interest rate risk in the banking book. The exercise applied sudden hypothetical interest rate changes to banks to see whether they are resilient. It looked at how the stress shocks affect the interest banks earn and the value of their books relate to traditional lending and deposit taking activities. We found that higher interest rates would increase banks' income. However, on the downside, they would decrease the economic value of banks' equity. In other words, the present value of their books. The exercise also looked at the models banks use to understand how their customers behave when interest rates change. We found that these models are largely set up for falling interest rates. This means that some banks might find themselves on the wrong foot in case interest rates rise. On average, a 200 basis points increase in interest rates would lead to a rise in net income of 10.5% by 2019 and a decrease in the economic value of equity of 2.7% also by 2019. The quantitative results of this exercise contribute to the amount of capital the supervisor requires each individual bank to hold. The qualitative findings help the supervisor assess how the bank is managed in terms of governance and risk taking. The good news is that most banks fared well and showed they could cope with interest rate shocks.