by MrBill » Sun 13 Aug 2006, 11:39:44
$this->bbcode_second_pass_quote('', 'B')lack Scholes wasn't that the trading system that led to LTCM disaster and subsequent bailout? Financial meltdown asian currency crisis?
Well, the math behind black scholes is pretty solid. It works on the basis that from every distinct price there is a chance that the price will go up or down. A 50% probability. So from there you can calculate the probability of a strike price being hit from any given starting point if you know the cost of money, the time value, the price of the underlying and the volatility. of course, you can only know historical volatility, not future volatility, so the one variable you have to guess at is implied volatility. Thousands of traders use this model or a version of it every single day to calculate future values. The question is always how fat are the tails? But again you're talking about forward looking models. YOu can never be sure WHAT WILL HAPPEN unless you're GOD and I assume you're not?
LTCM blew up for one simple reason. A couple of people thought they were more clever than the combined intelligence of the entire market, so they bet heavily against the market, thinking they could ''vacuum up nickels off the bottom of the pool that no one else could see". Unfortunately, being academics and not traders they forgot about liquidity and correlation. They
diworseified into assets that were correlated and then when liquidity dried up they were forced to close positions at a loss.
The 'good story' is that LTCM blew-up. There was very little contagion. Other firms learned from their mistakes. Risk management and credit officers are now much more aware of the limitations of black box models, and in short the industry learned from LTCM's mistakes. Also, I hope some academics learned a little from the lowly practioners? ; - )
MotherRock just blew up a few weeks ago. ABN Amro and some others will take a hit due to bad lending decisions, but other than that, barely a ripple. The market is evolving to deal with credit risks.
Oh and by the way, any losses from LTCM or MotherRock are by definition some other trader's win. Net, net, it is a zero sum game.
We all make mistakes. The biggest mistakes are made by those who think somehow they know more than the market. I think quite a few on PO are guilty of just that!!
The organized state is a wonderful invention whereby everyone can live at someone else's expense.