The year-long consultations on Basel II mirror the international popularity of capital requirements as a regulatory instrument. Yet, the impact of capital requirements on banks' behavior is not fully understood. The aim of this study is to contribute to this understanding by answering the following questions: How do banks adjust capital and risk after an increase in capital requirements? How do banks adjust their regulatory capital buffer over the business cycle? And, what is the impact of banks' charter value on the regulatory capital buffer?