Which of the following components of capital adequacy is/are mandatory as per Basel III norms?                      
I.        CET Capital                    
II.        AT1 capital                   
III.        CCB                  
IV.        CCyB

The countercyclical buffer (CCyB) is intended to protect the banking sector against losses that could be caused by cyclical systemic risks. CCyB will be deployed by national regulators when excess aggregate credit growth is judged to be associated with a build-up of system-wide risk to ensure the banking system has a buffer of capital to protect it against future potential losses. This focus on excess aggregate credit growth means that regulators are likely to only need to deploy the buffer on an infrequent basis . Banks will be subject to a countercyclical buffer that varies between zero and 2.5% to total risk-weighted assets . The buffer that will apply to each bank will reflect the geographic composition of its portfolio of credit exposures’