Ratings agencies S&P and Moody's downgraded JetBlue Airways after the carrier unveiled plans to raise more than $3 billion in debt, majority backed by its loyalty program, TrueBlue. Shares of the New York-based company plummeted 19%.JetBlue intends to raise $1.5 billion through a private offering of senior secured notes and an additional $1.25 billion via a term loan, secured by TrueBlue. It also plans to raise $400 million through a convertible notes offering, primarily to refinance existing debt.S&P downg ...