NEW YORK (TheStreet) -- Shares of Marathon Oil (MRO - Get Report) are down by 5.28% to $11.40 in midday trading on Monday, as the decline in oil prices drives some energy and related stocks into negative territory today.

Crude oil (WTI) is slipping by 2.64% to $43.48 per barrel this afternoon and Brent crude is falling by 3.59% to $43.74 per barrel.

The commodity is trading in the red as investors reexamined the impact of severe wildfire on Canada's oil output and following a report of another build in crude stockpiles at the delivery hub in Cushing, OK.

Crude inventories grew to 543.4 million barrels, the biggest increase since October 1929, Bloomberg reports.

A wildfire in Canada's Alberta oil sands region that began on May 1 has been threatening output. However, some analysts have reevaluated the threat of disruption to North America's crude supplies.

Alberta could lose about 650,000 barrels a day for three weeks, or almost 14 million barrels in total, Bloomberg added. However, Goldman Sachs analysts believe that "while significant, such disruption would have an only limited impact on overall North American crude inventories."

Marathon Oil is a Houston-based exploration and production company.

Separately, TheStreet Ratings has set a "sell" rating and a score of D on Marathon Oil stock. This is driven by multiple weaknesses, which TheStreet Ratings believes should have a greater impact than any strengths, and could make it more difficult for investors to achieve positive results compared to most of the stocks it covers.

The company's weaknesses can be seen in multiple areas, such as its poor profit margins, weak operating cash flow, generally disappointing historical performance in the stock itself and feeble growth in its earnings per share.

TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author. T

You can view the full analysis from the report here: MRO