MUMBAI, Dec 16 (Reuters) - Shares in India's GlaxoSmithKlinePharmaceuticals Ltd surged 20 percent in pre-opentrading to its maximum daily limit after GlaxoSmithKline Plc(GSK) said on Monday it plans to buy up to 20.6 millionshares to raise its stake in its Indian unit.
GSK is offering to buy the shares at 3,100 rupees per share,a premium of 26 percent over the market price on Friday, in adeal worth up to 629 million pounds ($1.02 billion) that wouldraise its stake in GlaxoSmithKline Pharmaceuticals to up to 75percent from 50.7 percent. (Reporting by Abhishek Vishnoi; Editing by Supriya Kurane)