General Motors Corp. reaches an agreement with some of its bondholders, just days after the auto maker’s debt-for-equity exchange fails, although it appears the deal will expedite rather than prevent a bankruptcy.

In its most recent regulatory filing, GM says the U.S. Treasury Dept. has agreed to offer bondholders a 10% equity stake in the restructured auto maker, as well as the option to purchase up to another 15% of its preferred stock in two installments.

But the deal hinges on a promise from bondholders not to oppose breaking GM into two parts, with the better-performing assets sold to a new company sponsored by the Treasury and underperforming assets wound down or sold.

“Implementation of this proposal would result in a new GM with a healthy balance sheet, putting the new company on a clear path toward long-term viability and success,” the auto maker says in a statement.

Calls to GM seeking additional details of the auto maker’s bankruptcy plans were not immediately returned.

The bankruptcy strategy GM intends to take commonly is called a “363 sale,” because it relates to section 363(b) of the bankruptcy code, and is exactly the path Chrysler LLC currently is pursuing under Chapter 11 protection.

A group of bondholders possessing roughly one-fifth of the $27.2 billion of outstanding unsecured debt reportedly have agreed to the deal. The offer expires at 5:30 pm May 30.

A debt-for-equity swap launched earlier this month and proposing bondholders take 10% of common stock in a restructured GM in exchange for forgiving $27.2 billion of the auto maker’s debt expired Tuesday.

Bondholders rejected the offer from the outset and countered with a plan giving them a 50% stake in the reconstituted GM.

According to this newest deal, bondholders still would get just 10% of the company after reorganization, while Treasury would own 72.5% and the UAW’s retiree health-care trust 17.5%, pending ratification today of a modified labor agreement by the rank-and-file.

The bondholders would have the option to buy 7.5% more of GM in preferred shares within the next seven years after reorganization and another 7.5% within 10 years. The UAW trust could get 2.5% more of GM in preferred shares.

Preferred shares carry precedence over common shares in the event of liquidation and typically also pay a dividend. Unlike common shares, they usually do not have voting rights.

jamend@wardsauto.com