The recent Chapter 11 bankruptcy filing by Sears Holdings Corp. offers another reminder, as if anyone in the industry needed one, of how fragile success in retailing can be.

Sears in its prime was as disruptive as Amazon.com is today, and, in fact, it pioneered shopping from home (via catalogs and the U.S. Postal Service) long before there was an internet. At the turn of the 20th century, Sears was distributing its “Big Book” to millions of rural Americans with limited or no access to retail stores. When more of the population shifted to cities, suburbs and towns, Sears added brick-and-mortar stores and continued to grow. Sears would go on to spend several decades as America’s largest retailer.

Kmart, which merged with Sears, Roebuck and Co. to form Sears Holdings in 2005, was another retail success story in its prime. Kmart (along with Walmart and Target) was part of a wave of new discount store chains that was launched in 1962. But Kmart was the first to scale up and become an iconic national chain, and during the late 1960s and early 1970s the company seemed unbeatable.

The 1980s saw Sears diversify, acquiring an insurance company and a brokerage firm, and launching its own credit card. But its core department stores were losing ground to discounters. Kmart was still the top discounter and was still growing, but Walmart was growing faster.

A major turning point for Sears, Kmart and Walmart came in early 1991, when all three companies reported their results for fiscal 1990. The result was that Sears was no longer the nation’s top retailer. Although it remained the larger company, when its other businesses were factored in, its retail business, Sears Merchandise Group, saw its sales grow just 1.2%, to $31.9 billion for the year. Kmart’s sales for the year grew 8.6%, to $32.1 billion, allowing it to edge past Sears’ retail operation. But Walmart surged ahead to take the retail sales crown, as its sales for the fiscal year grew 26% to $32.6 billion. Since then both Sears and Kmart have made numerous missteps, while Walmart’s growth has been unprecedented. But now new challengers have emerged, and Walmart and other retail giants are being forced to rethink their businesses again in order to remain on top. The lesson of Sears is that there is no future in doing otherwise.