After GE, Investors Are Watching These Debt-Laden Companies

The good times are coming to an end in the corporate debt market, and this week’s turmoil in General Electric Co. credit is a sign that things can get much worse.

That’s what a growing chorus of money managers are saying. About half of the $5 trillion market for investment-grade bonds now resides in the lowest tier of ratings. Many investors fear that as global economic growth shows signs of slowing, the rosy assumptions built into companies’ profit forecasts could prove wrong, and at least some of the lowest-rated high-grade debt may end up getting cut to junk.

Blue-chip company ...