GlaxoSmithKline, which has profit-sharing agreements with HGS on three drugs but a minimal shareholding, said Wednesday it is offering $13 cash per share for the company. A private offer last month by GSK at the same price was rejected by HGS management last month.
GSK said its offer was 81 per cent more than the HGS share price on April 18, before HGS disclosed the earlier private offer. HGS shares closed at $14.39 Tuesday on the Nasdaq exchange.
The tender offer, which is a direct approach to the target's shareholders, will remain open for 20 days. GSK said it hoped to complete the deal on a friendly basis.
GlaxoSmithKline shares were down 0.7 per cent at 1,414 pence in early trading.
Human Genome Sciences, based in Rockville, Maryland, has a 50-50 profit sharing agreement with GSK on the lupus drug Benlysta, which won regulatory approval in the United States and Europe last year. Benlysta accounted for $31.2 million of HGS' first quarter revenue of $47.1 million.
The two companies are also co-operating in late-stage development of darapladib, for the treatment of cardiovascular disease, and albiglutide, for type 2 diabetes.
"GSK values the long relationship it has with HGS and has clearly stated its preference to complete a transaction on a friendly basis in a timely fashion," the company said. "GSK remains willing to meet and review its offer with HGS at any time."