The NYSE's most recent disclosure of margin debt indicates a surge in trading in margin accounts, where total debt shot up to $231 billion as of December, up $58 billion from February or 30%, and also an increase of 4.5% from November. This is an indication that "animal spirits" have surged by about the same amount as the broader market since the market lows: in other words, speculation is now rampant, and, to make things even better, is very much on margin, or leveraged. And we all know what happens when levered speculative bets turn out not quite as expected. For those who may be confused, Dow Jones provides a useful primer of how a margin call feedback loop tend to make things ugly, fast.
A potential pitfall for those trading "on margin" is a sharp decline in stock prices, which can expose investors to margin calls, requiring them to post additional collateral lest their brokers sell their securities to cover the debt. A wave of margin calls can worsen selling pressure on stocks and was seen as partly to blame for the market's woes in the fall and winter of 2008-09.
But why worry - just like in 2006, every sellside (and in many cases, buyside) model now crashes if you plug in negative growth. At that point, coupled with a blue screen of death, the best outcome is to just reboot the computer and head to the nearest pub for a beer or seventeen. In the meantime, all problems will just resolve themselves on their own: especially if you have $100 trillion in discount window borrowings collateralized with recently defaulted securities from AIG's worthless portfolio. Oh, sorry, the Fed said ML III is worth at least par. So yes, all is good - Go back to drinking.