Kevin Warsh's warning of a potential slowdown and stagnation in the US banking system, along with his call for immediate action to reduce risks, may negatively impact the SPDR S&P Regional Banking ETF (KRE) in the short term. As the ETF is focused on regional banks, it is more exposed to the issues Warsh highlights, such as the divide between smaller and mid-sized banks and the 'too big to fail' banks. If the government does not take action to address these issues, KRE may face downward pressure.