Supervalu is going back to its wholesale roots, for better or worse.

When the struggling Eden Prairie, Minn.-based company unloads its four largest grocery chains in a pending $3.3 billion deal, the company will again rely on wholesaling for almost half of its business. Wholesaling has accounted for only about 23 percent of total sales in recent years.

The problem: Food distribution is a shrinking industry, as Supervalu can attest. Its own wholesale revenue has fallen 17 percent in the past 4 years, to $8.2 billion in fiscal 2012. A good part of the decline stems from the gradual loss of a big customer, Target.