The stock opened at Rs 160 on the BSE and soon fell as much as 7.82 per cent to hit the day's low of Rs 149.
Similar movement was witnessed on NSE, as the scrip plunged 8 per cent to touch an intra-day low of Rs 148.80.
In a regulatory filing to stock exchanges, PNB said it has detected some fraudulent transactions with financial implication of USD 1.17 billion (about Rs 11,334.4 crore), and the matter has been referred to law enforcement agencies for recovery.
The bank has detected some fraudulent and unauthorised transactions (messages) in one of its branches in Mumbai for the benefit of a few select account holders with their apparent connivance, PNB said.
Based on these transactions, other banks appear to have advanced money to these customers abroad, it said.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)