Shares of Supervalu, Inc.'s stock plummeted Tuesday on news of its third quarter performance and an announcement that the company lowered its fiscal 2011 guidance.

The Eden Prairie-based retail grocer reported a third-quarter net loss of $202 million, or 95 cents per share, on revenue of $8.67 billion. Analysts polled by Thomson Reuters had forecast earnings of 31 cents on revenue of $8.71 billion. In last year's third quarter, Supervalu reported $109 million in net earnings, or 51 cents per share, on revenue of $9.22 billion.

In an earnings release, Supervalu CEO Craig Herkert said that third-quarter sales were “softer than we had anticipated,” adding that “we invested heavily in promotional activities that proved to be less than effective.”

Consequently, the company lowered its fiscal 2011 earnings guidance to $1.25 to $1.35 per share-down from its reduced October prediction of $1.40 to $1.60 per share. It also said that it expects same-store sales to experience a 6 percent decline.

Supervalu has struggled in recent years amid tightened consumer spending, and its same-store sales have declined for the past 11 consecutive quarters.

On Tuesday, its stock closed down 11.6 percent at $7.59. According to The Wall Street Journal, Supervalu's stock reached its lowest levels since late 1984 on that day.

Herkert said in an earnings conference call that all of its major vendors have announced plans to pass along their increasing costs-and Supervalu expects to raise the prices of items at its stores throughout 2011 in response.

Supervalu recently announced plans to close 20 unprofitable stores within this fiscal year, which ends February 26, in order to “eliminate negative operating costs for a healthier start to the new year.” The company has also offered some corporate and office employees a chance to take unpaid time off, with managers' approval, through the end of the fiscal year.

Supervalu-which operates a network of about 4,280 stores-is Minnesota's fourth-largest public company based on revenue.