On the first anniversary of the terrorist attacks of Sept. 11, 2001, President Bush came to ground zero in lower Manhattan to solemnly commemorate the tragedy. As far as I know he never did anything like that again, and this year on the anniversary President Obama didn't do anything in particular.

But this week Obama did travel to ground zero to commemorate the first anniversary of the fall of Lehman Brothers. I guess presidents have short memories. I guess we all do.

I say all this with more than irony. To me, there's more than a calendar coincidence that relates the terrorist attacks to the Lehman collapse. Investors would be wise to understand the connection.

It's key for investors to understand that when something previously thought to be "impossible" actually happens, it changes the world, and makes other impossible things suddenly possible. Investors need to get correctly positioned for the newly possible.

But that's not easy -- most of us aren't like the queen in Alice in Wonderland who brags, "sometimes I've believed as many as six impossible things before breakfast."

As impossible as it was when that first airliner struck the first World Trade Center tower, minutes later something even more impossible happened -- another airliner hit the other tower. Then, within just two hours, both towers totally collapsed.

And perhaps the most impossible aspect of the whole thing is how few people died , considering how bad it might have been. When I saw the two towers in flames on television, I told myself "50 thousand." The actual death toll was 2,995.

Same thing with Lehman. The impossible led to even more impossibles. Forty-eight hours after Lehman fell, AIG did too. Days later, Washington Mutual. Then Wachovia. Within months, Citigroup and Bank of America were on the brink, as well.

And here, too, the financial equivalent of the death toll is far less that it might have been. At the worst of the banking crisis in the wake of Lehman's demise, it seemed the entire world financial system was going to stop functioning.

But somehow, impossibly, it didn't.

This sequence of impossibilities set in motion by Lehman was totally exploitable by investors who could see the impossible becoming suddenly possible. Nobody remembers it now -- and you're going to find this so impossible you're going to want to look it up to prove it to yourself -- but in the week after Lehman fell, financial stocks (as represented by the S&P Financial Sector index) actually rallied by a whopping 9.9%. That's because nobody was willing to believe the impossible -- after back-to-back collapses of Lehman and AIG, things just couldn't get worse.

But the impossible was possible. Things did get worse, and fast. In the following month -- that is, the month after that 9.9% rally -- financial stocks dropped 29.4%. And that was just the beginning. By the bottom in March, financial stocks had fallen 70.6%.