I love Trader Joe‘s and was thrilled when they came to Michigan a few years ago. But as a private company, they don’t file any SEC reports. Fortune Magazine does some digging and offers an inside look at their secrets.

The privately held company’s sales last year were roughly $8 billion, the same size as Whole Foods’ (WFMI, Fortune 500) and bigger than those of Bed Bath & Beyond, No. 314 on the Fortune 500 list. Unlike those massive shopping emporiums, Trader Joe’s has a deliberately scaled-down strategy: It is opening just five more locations this year. The company selects relatively small stores with a carefully curated selection of items. (Typical grocery stores can carry 50,000 stock-keeping units, or SKUs; Trader Joe’s sells about 4,000 SKUs, and about 80% of the stock bears the Trader Joe’s brand.) The result: Its stores sell an estimated $1,750 in merchandise per square foot, more than double Whole Foods’. The company has no debt and funds all growth from its own coffers.

If nothing else, they made “Two Buck Chuck” a famous wine.