The stock gained 3.98 per cent to Rs 1,191.50 at the BSE.
On the NSE, shares of Strides went up by 3.49 per cent to Rs 1,191.90.
Sun Pharma's scrip gained 0.75 per cent to Rs 911.90 but later pared the gains and was trading at Rs 899.50, down 0.62 per cent on BSE.
Sun Pharma and Strides have entered into a definitive agreement related to erstwhile Ranbaxy's 'Solus' and 'Solus Care' divisions operating in the CNS segment in India, Strides had said in a statement on Saturday.