A Black Friday sale at Nebraska Furniture Mart in Kansas City. AP Warren Buffet says that a small chain of furniture stores based in the Midwest is outselling the rest of the industry.

Nebraska Furniture Mart has just four locations: Omaha, Nebraska; Kansas City, Kansas; Clive, Iowa; and Dallas, Texas.

The Omaha location is "the highest-volume home furnishings store in the United States except for our new Dallas store," Buffet wrote in his most recent annual letter to shareholders, which was published on Saturday.

He said that the Omaha store raked in more than $44 million in a single week last year when it was running a promotion tied to Berkshire Hathaway's annual meeting with investors.

"If you repeat that figure to a retailer, he is not going to believe you," Buffet wrote.

The Omaha store typically generates about $9 million in sales weekly, according to his letter.

Warren Buffett. AP

Buffet didn't provide any revenue details on the Dallas store, which has been open for only a year. On its website, Nebraska Furniture Mart projects about $600 million in sales annually for that location.

By comparison, furniture retailer Restoration Hardware generated $2.1 billion in revenue last year and has 68 stores.

Despite Nebraska Furniture Mart having only four locations, each store and accompanying distribution center is more than 1 million square feet. Walmart supercenters, by contrast, are about 180,000 square feet.