Chief Executive Arthur Levinson opened an annual meeting with analysts and investors at a New York hotel on Monday by telling investors that Roche's offer of $86.50 per share does not "adequately reflect the value and future potential of Genentech's business."

Swiss drugmaker Roche Holding Ag is attempting to acquire the 44 percent of Genentech it does not already own for about $42 billion.

The world's second largest biotechnology company pushed up the date of the meeting to make its case ahead of the initial March 12 expiration date of Roche's tender offer.

"We believe we have the potential to create significantly more value for shareholders due to the strength of our products, our pipeline, our people and our track record," Levinson said.

Levinson did not state what he thought a fair price for the remainder of the company might be.

But with a late winter snowstorm as a backdrop, Genentech provided an avalanche of information about its research, future product prospects, standing in the biotech community and financial picture intended to demonstrate the inadequacy of the Roche offer.

The company forecast 2009 earnings, excluding items, of $3.85 per share, growing to $12.86 per share by 2018. Genentech expects U.S. sales this year of $10.7 billion, rising to $22.1 billion by 2018.

Genentech in January forecast a 2009 earnings range of $3.55 to $3.90 per share. Analysts on average are looking for 2009 earnings of $3.77.

Genentech shares were off 1.9 percent to $83.85 in morning trade on the New York Stock Exchange.

(Reporting by Bill Berkrot, additional reporting by Toni Clarke in Boston; Editing by Derek Caney)