The stock plunged 5.5 per cent to settle at Rs 24.05 on BSE. Intra-day, it dipped 7.26 per cent to Rs 23.60.
At the NSE, shares fell by 5.12 per cent to end at Rs 24.05.
"Shares of South Indian Bank fell more than 7.2 per cent in the day after the bank reported a weaker-than-expected numbers," said Hiren Dhakan, Associate Fund manager, Bonanza Portfolio.
The bank reported over 48 per cent decline in net profit at Rs 65.29 crore for the quarter ended June 30.
The bank's gross non-performing assets (NPA) rose to 1.85 per cent in the quarter from 1.71 per cent in March quarter and 1.50 per cent in the year-ago period.