Ranbaxy Lab's stock rose 4 per cent to Rs 650.7 at the BSE.
Similarly, shares of Sun Pharma jumped 3 per cent to Rs 854.
Sun Pharma and Ranbaxy yesterday got CCI's approval for their long-pending USD 4-billion merger, but with a condition that they will have to modify the deal by divesting seven key products to address monopoly concerns.
The regulator, which has ordered Ranbaxy to sell six products and Sun to divest one, will also appoint a monitoring committee to oversee compliance to the conditions put forth by it to ensure the merger does not hit competition.
In its order dated December 5 and made public yesterday, the CCI said it "approves the proposed combination... Subject to the parties carrying out the modification to the proposed combination".