Corporate Debt Coming Due May Squeeze Credit

When the Mayans envisioned the world coming to an end in 2012 — at least in the Hollywood telling — they didn’t count junk bonds among the perils that would lead to worldwide disaster.

Maybe they should have, because 2012 also is the beginning of a three-year period in which more than $700 billion in risky, high-yield corporate debt begins to come due, an extraordinary surge that some analysts fear could overload the debt markets.