Moody's considers downgrading Genentech ratings

Moody's said the biotechnology company's 'A1', or upper medium grade, ratings for senior unsecured notes due 2010, 2015 and 2035 are under review. If Roche is successful in its plan to buy Genentech, Moody's said, it will consider Roche's rating and the degree to which Genentech would become part of Roche, among other factors.

Moody's did affirm Genentech's 'Prime-1' commercial paper rating.

On Monday, Switzerland-based Roche proposed buying the remaining shares of South San Francisco, Calif.-based Genentech for $89 each. Roche already owns about 55.9 percent of Genentech.

Shares of Genentech fell 43 cents to $93.45 in afternoon trading.