Steps are being taken to protect bondholders from such shocks in the future, but many investors and market experts say that the changes may not be enough.

These covenants protect bondholders from more than six possible restructurings that would result in a credit downgrading.

The trustee bank is supposed to maintain a reserve fund worth 17 percent of assets to protect bondholders from defaults.

It carries with it high reserve costs that must be held to protect bondholders, as well as significant issuance costs associated with financing.

Commercial mortgages often contain lockout provisions after which they can be subject to defeasance, yield maintenance and prepayment penalties to protect bondholders.

The eurozone crisis reflects the aftershocks of that breakdown and the attempt to protect banks and bondholders across the continent.

Rather than face much higher borrowing costs, hundreds of companies have been considering proposals to help protect bondholders.

Even portions of the indenture designed to protect bondholders can wind up working against them.

The partners also secured a letter of credit from Fleet Bank, which is required to protect bondholders against default, and are investing some of their own equity.

The bonds will mature in 10 years and, interestingly, carry a sweetener intended to protect bondholders should Amazon.com's stock price plummet.