Duck season? Rabbit season? It's bank season. In the wake of this week's Massachusetts Massacre, President Barack Obama and congressional Democrats may place banks in their sights as they try to appease populist anger and come up with some sort of achievement to take into this year's mid-term elections.

No wonder Obama suddenly embraced the idea espoused by former Federal Reserve chairman Paul Volcker of a Glass- Steagall-like separation of banking and trading activities.

While legislative flesh still has to be put on the proposal — and it could easily be watered down — it marks a big shift in the administration's stance toward banks. It may even signal that the White House and congressional Democrats are getting the guts to finally tackle the question of too-big-to-fail firms and the future shape of Wall Street.

That leaves question marks hanging over the too-big-to-fail club. JPMorgan Chase & Co., Bank of America Corp., Citigroup Inc. and Morgan Stanley may all have to consider shedding or restructuring parts of their business. Who knows? Merrill Lynch & Co. or Bear Stearns Cos. may get a new lease on life.

Of all these firms, though, Goldman Sachs Group Inc. may be in the most danger. The bulls-eye on that firm's back is so big it may have to start thinking about contingency plans.

It didn't help that as Obama was detailing his proposals, Goldman was reporting the most profitable year in its history. Goldman said net income in 2009 climbed to $13.4 billion, compared to $2.3 billion in the fiscal year ended November 2008. Revenue for 2009 of $45.2 billion was double that of the 2008 fiscal year.

Underscoring the threat posed by Obama's proposal, which he dubbed the Volcker Rule, Goldman reported that fourth-quarter revenue from trading and principal investments of $6.4 billion accounted for two-thirds of overall firm revenue. While other firms such as JPMorgan have big trading operations, none is of the same significance to the overall firm as Goldman's. Even Morgan Stanley has over the past year been adding more traditional banking and brokerage operations.

Never mind Goldman's last-minute attempt to score some PR points by bringing down compensation as a percentage of revenue to about 35 percent. While that had Wall Street tongues wagging, Main Street will see only that Goldman still paid out $16.2 billion in 2009. That's a lot of bonus bucks in an economy with 10 percent unemployment.

So what is Goldman to do? One possibility: spin off some of its businesses, say its hedge-fund, private-equity and asset management operations, while taking the remaining investment- banking firm private, or vice versa.

Granted, that would be extremely difficult to pull off given the intertwined nature of the firm's many businesses. That was a point made on yesterday's earnings call by Goldman chief financial officer David Viniar.