NEW YORK (CNN/Money) - The two businesses are vastly different, but Sears' recent problems sure are reminiscent of the jam Lucent got itself into a few years back.

Until June, Sears was one of the few companies that investors were still in love with. Its earnings held up well last year and were growing fast through the first part of this year. Sears stock was at its highest level in four years.

Then things started to fall apart. Weak sales through the summer sent the stock lower. In early October the head of the credit and financial-products unit left the company. Shortly after that, Sears said its third-quarter earnings would come in a bit lower than expected due to weakness in its credit operations.

But when it reported earnings last Thursday, Sears missed its numbers by a country mile because of problems with its credit-card business. In an effort to get past the weakness in its retail business, Sears was extending ever more credit to customers while paying less and less heed to its customers' ability to repay debt.

Sears' stock fell 23 percent when the news came out. It's now trading 55 percent below its high of the year.

Those holding Lucent stock, who have seen the company's stock fall by 99 percent from its all-time high, can relate. As the stock market's go-go years came to a close, Lucent helped fuel its sales growth by extending generous financing to customers. Even as the economy idled and the telecom boom began to go falter, Lucent was extolling the benefits of vendor financing, telling investors in late 2000 that it planned to be more "like a bank." In 2000 it increased its loans outstanding to customers by $226 million to $1.8 billion.

Many of these customers -- outfits like Winstar and Leap Wireless -- were headed for the gutter.

"I don't think Sears happened as quickly as Lucent, peak to trough," said Jeff Matthews, president of the hedge fund Ram Partners. "But it's a valid analogy."

Like many retailers, Sears has long offered a proprietary card, which can only be used in its stores, but in 2000 it upped the stakes by offering a MasterCard. To help boost store sales, Sears MasterCard holders are given incentives to buy at Sears, but they can also use their card elsewhere. During the past year nearly 14 percent of Sears revenue -- and a whopping 58 percent of its profit -- came from its credit-card and financial services unit.

But that business came with a lot of baggage -- in the quarter, Sears had to add $189 million to its reserve for bad loans, accounting for much of the earnings miss. The fast-growing MasterCard business appears to be where the bulk of the trouble came from. At $10.8 billion, Sears' receivables -- claims against its customers -- in its MasterCard business were 250 percent higher at the end of the third quarter than they were a year earlier.

The credit-card business has been hard enough for companies focused solely on it, like Capital One. Sears, which entered the business right at the top, was far out of its element.

"They didn't have a history of running the business," said Suzanne Foley, an analyst at CreditSights.

But while a lot of Sears troubles are specific to it, it may, like Lucent, end up being the poster child for a larger malaise. It's not like the retailer is the only consumer-oriented company out there that's been extending credit to its customers.

Foley thinks Target's (TGT: Research, Estimates) relatively recent introduction of its Visa card program is troubling. The retailer, which garners about 17 percent of its operating income from credit-card operations, saw charge-offs (debt that's been written off) spike by 2.03 percentage points to 8.1 percent in September.

"Our delinquency rates and writeoffs are well within our expectations," said a Target spokeswoman. "We feel that we are very conservative and prudent."

Circuit City's credit-card operation saw delinquencies (payments past due) climb 0.3 percentage points to 8 percent and charge-offs increase 0.6 percentage points to 12.5 percent in September -- a signal that could "mark the beginning of worsening trends" at its finance arm, observed Prudential Securities analyst Mark Rowen. Circuit City (CC: Research, Estimates) did not comment for this article.

Ford's stock and bonds have fallen badly this year, chiefly because of investor concerns at Ford Credit, which helps Ford customers finance car purchases. "There seems to be this belief that Ford Credit could have a funding problem next year," said a Ford spokesman. "That couldn't be farther from the truth."

As for Sears, there may be more pain ahead. Its sales are suffering and its ability to integrate its recent acquisition of Lands' End looks increasingly problematic. Questions about what, exactly, was going on at its credit and financial-products business "could prompt at least an informal SEC query given the unusual circumstances and an earnings miss this big and this sudden with such material market implications," according to Gimme Credit analyst Carol Levenson. And management, which was apparently in the dark on the credit-card problems (even though CEO Alan Lacy used to run Sears' credit-card business), has lost some of its credibility.

A Sears spokeswoman said that the Lands' End transition is going well and that the company has "figured a worsening economy into the credit allowances and the outlook for the year." She said that it wasn't appropriate for her to comment on management credibility issues or "rumors and speculation" that the SEC might launch an inquiry.

Meantime, Americans are in debt like never before. As of the end of June, household liabilities were 17.2 percent of assets -- the highest percentage in the history of the Federal Reserve's data. Paul Kasriel, chief U.S. economist at Northern Trust, worries that, with the economy looking softer in the current quarter, the job market could begin to contract again.

"If people start losing their jobs," Kasriel said, "it's going to be hard for them to keep current on all that debt."

Of course, one can argue Sears' woes differ from Lucent's in some important respects. Consumers may be facing a little belt-tightening, but it's not like they're about to go away like a lot of Lucent's customers did. And the stuff that Sears sells will probably wear out a lot faster than all that excess capacity in the telecom equipment arena.

But maybe the biggest difference between the two companies is that while Lucent has only existed as an independent company since 1996, Sears has been around since 1886. You would think that 116 years would have been enough time to learn better.