Supervalu Inc. was a volatile stock even before the struggling company said it was for sale. It closed sharply higher on Friday but was up and down on Monday, ending the day flat. In after-hours trading, it was up more than 4 percent. The stock has a 52-week low of $1.68 and a high of $8.75. The company is seeking bids for the entire business, but suitors are said to have inquired about pieces of the company, and it may prove difficult to find one purchaser for 11 far-flung regional chains. The stock is off 71 percent this year.