When commercial real estate markets went bust two decades ago, bankers said they learned a hard lesson.

The latest earnings reports from U.S. banks suggest many, in fact, didn't.

Losses from loans tied to strip malls, office buildings, housing complexes, and the like are hurtling toward record levels not seen since the infamous savings-and-loan crisis.

But at some banks, according to the latest round of earnings reports, the commercial real estate crisis has already arrived. Those companies' worsening conditions could well foreshadow the heavy losses at regional lenders in quarters to come - and failures or takeovers for some.

"Commercial real estate in the United States of America is going to get worse consistently over the next several quarters," said Jamie Dimon, CEO of JPMorgan Chase & Co. (JPM), earlier this month when he discussed his company's earnings.

At SunTrust Banks Inc. (STI), an Atlanta-based bank with 1,700 branches, nearly 20% of the company's $8.2 billion in commercial loans tied to construction projects are nonperforming, or becoming uncollectable, as of June 30. At the same time last year, 6% of SunTrust's construction loans were in late-stage delinquency.

At KeyCorp. (KEY), a Cleveland-based regional bank with nearly a thousand branch offices, nearly 11% of the company's $6.3 billion in commercial construction loans were classified as nonperforming in the second quarter. During last year's second quarter, 3% of Key's construction loans were nonperforming.

At the height of the S&L crisis, which lasted into the early 1990s, late-stage delinquencies among commercial real estate loans peaked at 6%, while slightly more than 2% of outstanding loan balances became losses, according to data from RBC Capital Markets.

In the last decade, KeyCorp expanded its commercial real estate financing business beyond its 14-state footprint. SunTrust, like Key, wrote loans in overheated markets and both have struggled in recent quarters to stanch the flow of commercial real estate-related losses.

KeyCorp and SunTrust both said they've been reducing their exposures to commercial real estate. SunTrust said its commercial loan portfolio is stabilizing.

At other firms, problems have started to appear more recently.

Wells Fargo & Co. (WFC), for example, said 2.3% of its commercial real estate mortgages were considered nonperforming as of the second quarter, up nearly three-fold from 0.8% a year ago.

The San Francisco bank purchased its large teetering rival Wachovia Corp. at the end of last year, and Wells Fargo now holds $138 billion in commercial real estate loans, more than any other lender. Wachovia expanded aggressively into commercial real estate before falling victim to rising losses from consumer loans.

Nearly a third of Wells Fargo's total commercial real estate loans are tied to properties in California or Florida - two regions among the hardest hit by the real estate depression.

Wells Fargo did not immediately respond to a request for comment.

The other top commercial real estate lenders include Bank of America Corp. (BAC), with $105.5 billion, and JPMorgan, with $67.6 billion, according to data from Standard and Poor's.

Should problems with commercial real estate loans keep ballooning, bankers and analysts say the trend could force firms now beset by losses to fall into competitors' arms.

Just Monday, Harleysville National Corp. (HNBC), a Pennsylvania bank with 85 offices that's been rocked by real estate construction loans, agreed to sell itself to Buffalo-based First Niagara Financial Group Inc. (FNFG) for $237 million in stock.

Harleysville's recent struggles show how quickly commercial real estate troubles can appear.

In April, homebuilder THP Properties, "a significant borrower" of Harleysville National's, abruptly declared bankruptcy, the bank disclosed in a filing. Until then, THP's loans had been considered in good standing.

Twenty years ago, during the S&L crisis, defaulting commercial property construction loans tagged thrifts with billions in losses. Nearly 750 thrifts shut their doors or were sold under pressure.

(Joe Bel Bruno contributed to this story)

-By Marshall Eckblad, Dow Jones Newswires; 212-416-2156; marshall.eckblad@dowjones.com