Zenotech Laboratories was locked at the 5% upper limit at Rs. 45.25 after Sun Pharma made an open offer to buy 9.7 million shares at Rs. 20.87 pursuant to the Ranbaxy merger deal.
Total traded quantity on the counter stood at over 3677 shares.
The BSE benchmark index thereafter recouped losses and finally ended on a flat note at 27,957 - down 18 points.
The NSE Nifty moved in a range of near 100-points. The Nifty from a high of 8,550, tumbled to a low of 8,454, and eventually settled at 8,491 - down one point.