Shareholders tend to love big repurchase programs, figuring they support the stock price.
The ratings review will focus on the cash demands of the new repurchase program.
The company has bought about nine million shares at an average price of $41.67 a share under a 10-million-share repurchase program authorized in 1988.
Initially, the repurchase program will affect only the exchange debentures due in 2007.
In addition to using their own cash, companies may borrow money in order to carry out repurchase programs.
The company said it was beginning the repurchase program because it felt the stock had been undervalued.
It is evidently the largest such repurchase program ever announced at one time.
No time limit was set for the new repurchase program.
Initially, the repurchase program will affect only the exchange debentures.
But repurchase programs can also have a huge impact on a company's cash flow.