Looks like all those option adjustable rate mortgages (ARMs) weren’t such a good idea after all: 1% teaser rates and loans that grow, rather than shrink, over time just aren’t meant for questionable borrowers buying overpriced homes.

Newport Beach-based Downey Savings (DSL), the fifth largest originator of option ARMs, was seized by federal regulators late Friday. The scraps were sold to US Bancorp (USB) for a song, which included almost $10 billion in deposits. Pomona First Federal, another Southern California lender highly levered to the real estate market, was also taken over by Minneapolis-based US Bank.

According to Bloomberg, the 2 failures will cost the FDIC more than $2 billion to clean up. US Bank agreed to assume the first $1.6 billion in losses from the banks’ loan portfolios, but anything above that will be split with the FDIC.

Each of the 5 biggest option ARM writers have now collapsed. Countrywide was purchased by Bank of America (BAC) in July; IndyMac collapsed into the arms of the FDIC just a few weeks later; Washington Mutual was scooped up by JP Morgan (JPM) in September; October saw Wells Fargo (WFC) best Citigroup (C) for the right to buy Wachovia (WB); now Downey is gone.

It didn’t have to end this way.

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Traditionally meant for savvy borrowers capable of managing multiple payment options, Washington Mutual is often cited as having invented the option ARM in the early 80s.

The loan gives a borrower a series of payment choices, the lowest of which is so tiny the loan balance increases each month instead of being paid down. ARMs also typically include a teaser rate -- sometimes as low as 1% -- which can last anywhere from1 month to 5 years.

Ideal for real estate investors, salespeople with choppy income or families hopping between 1 and 2 earners, the flexible payment options and strict underwriting guidelines made option ARMs some of the best performing loans on the market.

But that was then.

As securitization took off, interest rates fell and the housing market heated up, lenders turned these once-safe loans into jet fuel for their ballooning mortgage businesses.

Option ARMs came to epitomize the irresponsible lending that ran rampant during the boom. Lenders abused their ability to qualify borrowers at absurdly low rates, jamming them into homes they could never afford once their mortgage payments rose.

Due to their complexity, mortgage brokers and loan officers rarely bothered to make sure borrowers fully understood the loan terms. A complete explanation would have lasted hours, providing adequate cover for the fraud already so prevalent in the business.