Swiss drugmaker Roche Holding AG raised its offer to buy out Genentech Inc to $93 from $86.50 a share, or $45.7 billion, in a move to clinch the remaining 44-per cent stake in the US biotech group. Genentech's board had deemed the previous offer as too low, asserting that the biotech group's value was closer to $112 a share. (See: Roche makes a $43.7-billion bid for Genentech / Genentech rejects Roche's $43.7-billion takeover offer as too low)

Roche already owns about 56 per cent of Genentech's shares. Shares of Genentech jumped more than 10 per cent on the news.

"Based on conversations with Genentech shareholders, we believe that there is a strong sentiment to bring this process to a conclusion," Chairman Franz Humer said in the statement. "As a result, we are increasing our price to $93 per share to maximize shareholder participation and will proceed quickly to complete all necessary financing. We now look forward to successfully completing the transaction.''

Genentech issued a statement Friday advising shareholders not to act on the latest offer until a special committee convened by its board had thoroughly evaluated the deal. The company added it expected the committee to make recommendation on the offer promptly.

Genentech said in a US Securities and Exchange Commission filing Tuesday that it had 466,159,047 shares outstanding - excluding those owned by Roche, directors, officers and others - and believed that minority shareholders would have to tender at least 233,079,524 shares for Roche to get a majority of those shareholders.

If Roche owns 90 per cent of more of the outstanding shares when the deal is consummated, it would make an immediate cash payment equal to the price per share paid in the offer and a future cash payment based on a valuation, according to a squeeze-out provision in another SEC filing last month.

According to The Wall Street Journal last week, Roche could have more than $50 billion available to finance the deal.

An original offer of $89 a share was soundly rejected by Genentech's board last August. In late January, Roche launched a hostile takeover bid with a lowered price of $86.50, citing a weakened global economy. The $86.50 offer was set to expire on 12 March. On Friday, Roche said about 500,000 shares had been tendered.

Best known for its cancer-fighting therapies Herceptin and Avastin, Genentech is one of the world's largest and oldest biotechnology firms, with a market capitalization of about $95 billion. Roche is Genentech's largest shareholder and currently own 55.8 per cent of the biotech.

Of Genentech's seven board members, three are independent directors, one is the Genentech chief executive and the three others are designated by Roche. Genentech CEO Arthur Levinson pointed out at a recent conference in New York that Genentech-developed products accounted for 66 per cent of Roche's top-selling drugs in 2008.