Punjab National Bank scam involving diamond traders Nirav Modi and Mehul Choksi. Bank employees issued fraudulent Letters of Undertaking (LOUs) without collateral to allow Modi and Choksi to secure overseas loans. The fraud was discovered in January 2018, totaling over $1.77 billion. Investigations are ongoing by the Central Bureau of Investigation and other agencies into the individuals involved and systemic failures that allowed the fraud to occur. The scam has severely damaged confidence in Punjab National Bank and highlighted weaknesses in oversight and controls in the Indian public banking sector.