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Borders said Monday it will close its remaining 399 stores and sell its assets to a liquidation firm. The No. 2 U.S. bookstore chain, which has operated under bankruptcy protection since February, blamed industry challenges, e-readers and the economy for its demise.

Borders joins Blockbuster, Circuit City and Linens n' Things on a list of retailers with more than $1 billion in assets that have succumbed to bankruptcy in recent years. Many stronger chains, including Ann Taylor (ANN) and Starbucks (SBUX), have shuttered underperforming stores to bolster profits. Others like Wal-Mart (WMT) are focusing on smaller store formats for future openings. At shopping centers nationwide, the vacancy rate recently hit a two-decade high.

Even liquidators are liquidating. On Tuesday, Ontario-based closeout chain Liquidation World, which exited the U.S. last year, sold its remaining operations to Big Lots (BIG) for a scant $20 million, or less than $225,000 per store.

Which remaining retailers are vulnerable? There are two ways to answer that question. The easiest way to find companies with near-term liquidity concerns is to look for ones with credit ratings that suggest vulnerability -- for Standard & Poor's ratings, CCC and worse. But such ratings are uncommon. Sbarro and Perkins /Marie Callender, restaurant chains rated D, filed for bankruptcy in April and June, respectively.

Barneys is rated CCC with a "negative" outlook, suggesting its rating may be lowered. It has a strong brand but a small store base, a narrow market, heavy debt and "very thin" credit protection measures, according to S&P. Founder Barney Pressman's family lost control of the designer clothing chain in 1998 and following a bankruptcy and brief ownership by Jones Apparel Group, it was sold to Istithmar, an investment vehicle of Dubai government, which has larger concerns than Barneys, including those palm-shaped islands it built when its real estate prices were more than double today's level.

Beyond companies with near-term debt concerns are many with long-term operating challenges. Here are a few that aren't in financial trouble but are struggling to find new customers and turn profits:

- Build-a-Bear Workshop (BBW) has a cash surplus, but its sales are shrinking and profits have disappeared. Perhaps it can do without the Fifth Avenue store in Manhattan that's bigger than Apple's nearby flagship.

- Zale (ZLC) shares sells for about what they did in 1994. Back then the mall jeweler turned a yearly profit of $21 million. Over its last two fiscal years it lost more than $250 million, and more sizeable losses are projected for this year and next.

- Frederick's of Hollywood (FOH), it seems, still exists. Last week, the maker of the Extreme Cleavage bra announced the opening of a flagship location in Abu Dhabi. The company's income statement is anything but flattering, with steep losses showing since 2007. The entire business is valued at about $25 million.