The debt offering takes advantage of the market’s low interest rates, and will help fuel Viacom’s recently announced plan to double its stock repurchase effort to $20B — including $3B to take place in 2013. The decision to raise overall debt led Moody’s Investors Service to lower Viacom’s senior unsecured rating to Baa2 from Baa1. The buy-back “appears to be a one-time effort to smooth over the anemic growth by returning more capital to win the favor of shareholders,” Moody’s said. The plan has worked so far: Viacom shares are up 10.2% following the repurchase announcement. As for the debt, Viacom says that it will consist of three offerings with $500M in senior notes paying 2.5% due in 2018, $1.25B in senior notes at 4.25% due 2023, and $1.25B in senior notes at 5.85% due 2043. Citigroup Global Markets; J.P. Morgan Securities; Merrill Lynch, Pierce, Fenner & Smith; and RBS Securities are the joint book-running managers.