S&P Global Ratings gave a slight upgrade to GulfMark Offshore after the company last week pulled out of a tender offer to buy back its unsecured debt below face value.

S&P said the its corporate credit rating on the US-based offshore vessel owner was raised to 'CCC-' from 'CC'. The rating outlook remains negative.

The senior unsecured notes were also upgraded to 'CCC' from 'CC'. S&P says it expects a "substantial recovery" of at least 70% to 90% for debtholders in the event of a payment default.

S&P made the upgrade after the company announced last week that it would end a tender offer to buy $300, of its 6.375% senior unsecured notes due at 2022 at below par. GulfMark ended the offer due to a lack of investor interest and the inability to hit a minimum threshold of $250m required to close the transaction.

S&P's negative outlook on the company reflects the continuing distress in the offshore sector with the expectation that GulfMark will continue to see depressed dayrates and utilisation levels into 2018. S&P said GulfMark should consider another distressed debt exchange or restructuring during the next six months.