The article examines how financial crises in one country can affect other countries through the banking system. It looks at different ways this can happen, like changes in collateral value and bank stability. Recent studies show that exposure to the same funding source is important, while bank runs are not a major cause of financial problems. Public guarantees as a vulnerability to financial shocks are still debated. The study finds that risks from a common lender have decreased after crises like those in Mexico, Asia, and Russia.