Just when some traders thought oil had hit bottom, crude plumbed new depths on Monday.

Signs continued to mount that oil supplies are overwhelming demand, prompting investors to send the price of U.S.-traded crude to a six-year low. Days after the International Energy Agency raised alarms about the U.S. running out of storage capacity, a report by data provider Genscape Inc. indicated stockpiles had increased last week at Cushing, Okla., a key storage hub, according a broker who had reviewed the report.

...