GulfMark Offshore has put pen to paper on a restructuring agreement with lenders that will see bondholders take a 36.7% stake through a Chapter 11 bankruptcy to be filed by Sunday.

The agreement will sweep away $430m in debt with $27m in annual interest payments. It also calls for a $125m cash injection through a rights offering for another 60% in the equity of a reorganised GulfMark, leaving existing shareholders with a small fraction of the company's stock.