New Delhi: Shares of Lupin on Monday fell by 4 per cent after the company said it has been cautioned by the US health regulator that its Somerset (New Jersey) facility may be subject to regulatory or administrative action. The shares declined 3.92 per cent to close at Rs 754.50 on BSE. During the day, it plunged 5.59 per cent to Rs 741.35. (PTI)