TJX Companies (NYSE:TJX) is one of the most successful big box retailers in the U.S. The company operates the biggest off-price department stores in the U.S. and abroad--under the T.J. Maxx, Home Goods, and Marshalls brand. TJX Cos boasts 3,200 steadily growing stores with widening margins and a dividend that's growing nicely.

Different operating model
But, perhaps what sets the company apart from other large retailers in the country such as Sears Holdings (NASDAQ:SHLD), and J.C. Penney (NYSE:JCP) is its unique operations strategy. TJX says that its merchandise is 20%-60% cheaper than comparable goods in department stores and specialty retail shops.

The company manages its inventory in a way that is strikingly different from the average big retailer, by buying much less merchandise, and turning over its inventory more frequently than its peers. This helps the company to keep its goods fresh and minimize the risk of holding the items for too long, which might increase the risk of the goods losing their allure to customers and forcing the company to resort to large product markdowns.

TJX is able to offer fire sale-like prices to its customers because it has become adept at hunting for great deals with desperate clothing manufacturers and apparel stores. The company has a team of 800 buyers who scour the markets looking for manufacturers with order cancellations, as well as manufacturer overruns and closeouts. Once TJX buyers finds a suitable candidate, it's able to buy its merchandise for a song, and pass on the huge cost savings to its customers.

TJX has also borrowed a play from Costco, the largest warehouse retailer in the U.S., and does not advertise its goods--which is, of course, a good thing, since the brands from which the company buys its cheap merchandise would not want to be identified with cut-price goods.

TJX's stores are bare-bones affairs, and are quite often messy and cluttered. But, its customers, mostly working moms, do not mind all these penny-pinching measures, and flock in droves to its stores to hunt through its marked down merchandise. The company's lean operations leave it with a fatter profit margin than its retail peers.

TJX Cos unique goods exhibit markedly lower overlap with Amazon's--just 17% compared to the average 46% overlap for the average retailer. It is this kind of uniqueness, coupled with the company's rather mysterious sourcing strategies, that led William and Blair analysts to conclude that the company is one of retailers least susceptible to Amazon and its disruptive pricing habits.

Net losses aside, are Sears and J.C. Penney good buys at the current prices?
Beleaguered big box retailer Sears Holdings(NASDAQ:SHLD) and J.C. Penney(NYSE:JCP) have been struggling to keep afloat in the face of intense competitive pressure from online operations such as Amazon. Shares of both companies have fallen so much, and look like good value--if only the companies behind them would survive long enough. So are Sears and J.C. Penney shares good value, or just value traps?

Let's start with Sears because the company has been seeing a lot of action lately. Sears' shares had been down for much of the year, but surged 30% last week, on news of insider buying and a Forbes article touting that Amazon should buy the company. On a purely retail point of view, J.C. Penney is, perhaps, a better turnaround bet than Sears because Sears's main attraction to investors lies in its extensive real estate properties rather than its retail business, while J.C. Penney's retail operations may be sputtering back to life.

Sears' first strategy was to package its stores as potential data centers, with Bruce Berkowitiz, a major Sears shareholder, opining that the company's shares were worth at least $160 on the strength of its real estate properties alone. But, the potential of Sears' real estate properties as data centers is questionable. An empty store in a shopping mall located in the middle of the suburbs is highly unlikely to be a suitable data center due to limited space and lack of cheap power.

Sears has had 119 closed stores available for sale for months now, but not a single store has been sold to date. Rumors have been circulating that Amazon might buy Sears and convert its stores into distribution centers. At this point, the Amazon news is mere speculation, and no Amazon official has commented on it yet. If it turns out that Amazon is actually interested in Sears' stores, then Sears shares might rise considerably. But, right now the shares are too volatile with a high short interest of 20.3%, making them less attractive as investment instruments.

J.C. Penney has been making inroads in its turnaround bid ever since former chief executive Myron Ullman returned. Its gross margin has risen to 28.4% and the company looks like it's on a strong recovery path. But, investors don't seem to acknowledge these positive moves, and the shares are down 46% from where they were a year ago. Moreover, the company is still showing worrying weaknesses in its balance sheet, including a declining net operating cash flow which fell 40% last-quarter to $383 million, and a falling ROE, or return on equity, which is usually a signal of serious underlying trouble.

J.C. Penney shares are, therefore, still a risky gamble at the moment. But, long-term investors should keep an eye on the company and see whether it will announce significant improvements in its upcoming quarterly report. If it manages to do so, then shares could be a decent investment at the lower price.

Foolish bottom line
Sears and J.C. Penney have unfortuntely lost their edge and are now only suitable for sheer speculation, a truly un-Foolish approach. TJX Companies, on the other hand, has maintained a unique competitive advantage at a time when many large retail stores seem to be faltering. Long-term investors should take a deeper look.

Joseph Gacinga has no position in any stocks mentioned. The Motley Fool recommends The Motley Fool owns shares of Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.