We're reminded once again that Wall Street has a difficult time with moderation, and taxpayers are likely to pay the price of its most recent excesses for years to come. Let's hope regulators will soon provide us with more confidence that our tax money is being put to good use.

Minnesota Commerce Commissioner Glenn Wilson, who worked in the banking and mortgage businesses before becoming a regulator, succinctly described the impact of the most recent cycle of irresponsible greed in an interview with Star Tribune business columnist Neal St. Anthony: "You have to assume people with that kind of money are investing it wisely, but about every 10 years they go nuts.''

They've done it again, and now the federal government is taking extraordinary steps to try to avoid what former Treasury Secretary Lawrence Summers told the Wall Street Journal is a "very real risk'' of the 2008 mortgage and credit meltdown turning into "the most serious economic downturn in a generation.''

A key player in the rescue effort is Federal Reserve Chairman Ben Bernanke, who's considered the world's leading expert on the Great Depression. (We're not sure if that should make us feel more confident, or less.)

The Fed has cut interest rates, forced the fire-sale acquisition of Bear Stearns by JP Morgan and made available more than $200 billion in credit to investment banks and securities dealers. The hope is that those moves and others will calm investors, spark lending and prevent credit market paralysis.

No one can predict whether the dramatic moves will work, which is why other more drastic -- and much more expensive -- proposals have surfaced on Capitol Hill and within the Treasury Department. At least some of those proposals would involve billions of dollars in federal spending on a massive bailout of the financial services industry.

The price tag is so high because the financial services sector has become a giant, sprawling player in the U.S. economy. About $1.3 trillion in consumer credit is now linked to finance companies, nonfinancial businesses and pools of debts that were transformed into securities. Much more highly regulated consumer banks, meanwhile, hold $809 billion in outstanding consumer debt, according to a January estimate by the Fed.

The consulting firm Global Insight found that for every dollar of capital in commercial banks, "nonbanks" had only 20 cents of capital. That means those firms have far less of their own money at risk than conventional banks.

With so large a piece of the economy at stake in loosely regulated businesses, and with more and more taxpayer dollars at risk, new government oversight is almost assured. There are legitimate concerns that more regulation could stifle innovation, but right now we need fewer new financial instruments and more confidence that financial firms aren't taking unnecessary risks.

Otherwise, we're likely to see Wall Street go nuts again.