Roche Holding offered  $43.7 billion to take over the remaining shares of Genentech Inc.

Roche, owns 55.9 percent of the Genentech Inc. and is  offering $89 per share, 8.8 percent above the closing price  on 18th July and 19 percent above the price a month ago. It's the largest offer ever made by a Swiss concern for a takeover.

It will generate more than $15 billion in annual revenue and employ a total of about 25,000 people in the U.S., the statement said. The company did not specify how many of the 10,700 employees of Genentech would be retained.  Roche has been a partner with Genentech since 1990.

Roche said the takeover would improve operational efficiency by reducing complexity, eliminating duplications and increasing scale in the United States. Roche said Genentech's San Francisco site would operate as an independent research and early development center and become headquarters of combined U.S. commercial operations.

The statement said it expects the Genentech Board of Directors will establish a committee of independent directors to evaluate Roche's proposal with the assistance of independent outside financial and legal advisers. Genentech board members who are employees of Roche will not participate in the evaluation of the proposal, it said.

The statement said Roche plans a cash merger between Genentech and a Roche subsidiary and that all currently outstanding shares and options of Genentech other than shares owned by Roche would be converted into cash. Precise terms will be determined through negotiations with the independent directors, it said, adding that it expects the merger would be subject to the approval of holders of a majority of the Genentech outstanding shares not held by Roche. "Roche expects to complete the transaction as soon as possible following negotiation of a definitive merger agreement," it said.