This week is an interesting case study in something I've noticed in the short time I've been trading as a hobby: the market almost always
overreacts to news and events, then partially retraces later in the session or the next day.
There were two significant events this week: the Sunday announcement of JPM's takeover of Bear for $2/share (which had been trading at $80 two weeks earlier), and GS and LEH announcing earnings before Tuesday's session and beating the estimates.
So, Sunday night you just know the market's gonna get slaughtered on Monday. But if the market were efficient, wouldn't you think the adjustments would either be already priced into the market's much lower opening, or at the very least settle out in short order given everyone had this news prior to opening? Nope, as per usual people panic, overreact, and you get a nice steep decline all frickin' day long (not that I'm bitching, I made a killing on shorts Monday).
Now, what seems to happen a lot of the time is the next day the stocks in question regain some of their losses, as people have a chance to take a deep breath and realize things might have been beaten down too far and go shopping for bargains. However, this Tuesday you had a second piece of news to react to... GS and LEH beat earnings (never mind that they're down 50% from last year

). Does the earnings news justify a major rally? Of course not. The fundamental situation hasn't changed, the credit crisis is still there, and Lehman could easily find itself the next BSC. But, as usual the market overreacts, and the effect is magnified by the retracement of Monday's decline. Result: one of the best days the market has seen in a while.
So now it's Wednesday. What happens? People begin to realize that the size of yesterday's rally was unjustified given the fundamentals, and where do prices go? You guessed it, South.
Where does the market go from here? Who the hell knows, but if every day were as predictable as the last three we'd all be billionaires. I'm just parking my cash waiting for the next piece of news that the market can overreact to so I can ring the cash register again.