After a weak opening, the stock further slumped 8.45 per cent to Rs 83.40 on BSE.
At NSE, shares of the company tumbled 9.63 per cent to Rs 82.55.
Officials said Shah was arrested yesterday under the provisions of the Prevention of Money Laundering Act (PMLA) as "he was not cooperating in the investigation".
Reacting to the development, FTIL said in a statement, "We fail to understand why such a coercive step was taken against by the ED when Shah has been fully cooperating with the investigation.