The tender offer of Rs 3,900 per share is at a premium of 27.9 per cent to Friday's closing price of Rs 3,049.35 per share on the NSE.
GSK Consumer shares were up 20 per cent at Rs 3,651 at 09.15 a.m. This is a new 52-week high for the stock. Shares in GlaxoSmithKline Pharma, another group firm, also surged 7 per cent to Rs 2,142 on the news.
The outperformance in GSK group stocks was in contrast to the broader markets, which traded with muted gains. At 09.15 a.m., the Sensex traded 78 points or 0.4 per cent higher at 18,585 while the broader Nifty advanced 19 points to 5,645.
Analysts told NDTV Profit that the 28 per cent premium is tempting for investors and a good response should be expected to the open offer. Delisting is an option in case there is full tender in open offer, they said.