It comes after the firm swung to a loss in its second quarter results released last week. Noble has been hit by tumbling commodity prices over the last two years, questions over its accounting practices and a string of downgrades by credit ratings agencies.
Moody’s first cut Noble’s credit rating to junk in December.
Joe Morrison, a Moody's vice president and senior credit officer, said that the downgrade came despite the group's successful refinancing of its bank facilities.
"The refinancing of the credit facilities and receipt in March of $750m in proceeds from the sale of its remaining stake in Noble Agri Limited has alleviated the immediate pressure on the company's liquidity."
"However, the short-term nature of these facilities and its sizeable maturing debt over the next 1-2 years mean its liquidity remains constrained."
It's a stark contrast to rival credit ratings agency Fitch, which said today that the commodity trader's liquidity squeeze is likely to be temporary. It expects Noble to benefit from the recent $500m rights issue and working capital reductions.