Swiss drugmaker Roche Holding AG (ROG.VX) said Thursday it has agreed with Genentech Inc. (DNA) to buy the 44% of the U.S. biotech company that it doesn't already own for around $46.8 billion.

Roche, based in Basel, said it expects the transaction to be accretive to earnings in the first year after closing.

The agreement ends a nearly eight-month battle, in which Genentech repeatedly rejected Roche's offer.

Last Friday, Roche increased the offer price to $93 a share. The agreement reached now is for a slightly higher price of $95 a share.

"We believe this is a fair offer for Genentech shareholders," said Charles Sanders, chairman of a special committee of independent Genentech board members in a statement. "We look forward to working with Roche to complete the transaction as expeditiously as possible."

Roche expects the combination to generate annual pre-tax cost synergies of approximately $750 million to $850 million. Synergies will be driven by reducing complexity and eliminating duplicative functions and processes in areas like late stage development, manufacturing, corporate administration and support functions, Roche said.

Chief executive Severin Schwan had told shareholders that driving the integration of the two companies will be Roche's main goal this year, after the merger has been completed.

Roche shares closed Wednesday at CHF145.50, down 10% year-to-date, and thus outperforming the European sector at large, which is down 15%.

Company Web site: www.roche.com

-By Anita Greil, of Dow Jones Newswires; +41 43 443 8044; anita.greil@dowjones.com