The accusations levelled against staffers of Punjab National Bank (PNB) — that they arranged for letters of undertaking to be provided to foreign branches of Indian banks to benefit companies controlled by jeweller Nirav Modi and associates — have thrown up important questions about bank management and regulation in India. While the sums involved are large — the total sum being examined in relation to the fraudulent letters of undertaking is $1.8 billion — it is unclear how much has actually been taken out of the system. It is also an open question whether PNB is on the hook for