Jan. 11 (Bloomberg) -- GlaxoSmithKline Plc and Novartis AG are considering bids for Serono SA, the region's largest biotechnology company, with a market value of $13 billion, people involved in the offers said. Serono, the maker of multiple sclerosis treatment Rebif, in November hired Goldman Sachs Group Inc. to explore the company's options. Glaxo, based in London, and Basel, Switzerland-based Novartis have yet to decide on a price, said three people who declined to be identified because the plans are confidential.
