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Jim Surowiecki has a great line this week, in his column on stock-market volatility:

For now we're stuck in a Yeatsian market: The best lack all conviction, while the worst are full of passionate intensity.

The sentiment here is spot-on. Right now we're in a William Goldman market: nobody knows anything. In such a situation, one might expect that traders and investors both would tread cautiously, and the market would make no sudden moves. Instead, volatility has gone up dramatically, and 2% swings in the stock market are commonplace.

 It's worth noting, however, that Surowiecki's column is grounded in a pretty strong version of the efficient markets hypothesis. He talks about "real news" twice and "new news" once, as drivers of stock prices, and contrives to act surprised that sometimes stocks move dramatically even when there's no news of either description.

But in order for this to be at all surprising, you have to believe that stock prices reflect all the information in the market, and that in order for stock prices to change, new information (aka "news") has to arrive. It's a belief which is understandably attractive to journalists, who traffic in news. But it's also a theory which remains stubbornly immune to empirical validation.

Along any given timeline, there will be points at which big news events happen. And there will be points at which big stock-market moves happen. But the two don't overlap nearly as often as you might think, and indeed when they do overlap, the direction of the stock-market move is often counterintuitive.

As Surowiecki says, what we're witnessing right now is symptomatic of stock-market behavior broadly. Market participants tend to "herd"; down markets tend to be accompanied by increased volatility; and if anybody wants to make money in this market they're going to have to be willing and able to change their directional bets frequently.

There's also the fact that a credit crunch is a classic crisis of confidence, which means that big stock moves really are news, in and of themselves. Creditors are in control right now: Any leveraged company that can't fund itself in this market is toast. And creditors keep a very close eye on the stock market: If a leveraged company's share price is strong, there's probably relatively little to worry about. If it's weak, however, that implies that the equity cushion is being eaten away fast, and that it might not be such a good idea to roll over that company's debts.

If the stock of Lehman Brothers (LEH), say, is falling, then, that's in and of itself reason for its creditors to be worried -- which in turn is reason for the stock to fall further.

But the real lesson to be learned from all this stock-market volatility is that nearly everybody attributes far too much importance to one-day or one-week or one-month moves in stock-market indices. Writes Surowiecki:

Precipitous falls in the market have frequently been followed immediately by sharp rallies, and vice versa. And, while some of these moves have been occasioned by real news, more often it's been impossible to tell just what made investors so damn exuberant or so gloomy ...

In this market, the same traders who on Tuesday seem convinced that the apocalypse is nigh are, on Wednesday, just as sure that we've weathered the storm.

Who says that investors are being particularly exuberant or gloomy? The only evidence is short-term moves in the stock market, and once again you need to believe in some kind of efficient markets hypothesis to work backwards from a market plunge to gloomy investors.

Yes, it's conceivable that if a whole bunch of investors woke up one morning in a particularly gloomy and pessimistic mood, then the stock market would fall. But that's not what happens in real life. Think back to the last time you bought stocks: Were you particularly happy or exuberant? What about the last time you sold stocks: Were you gloomy or sad? Things are never as simple as that. The concept of "market psychology" is a wonderful invention for journalists desperate for a narrative, and is a great sales tool for people who believe in technical analysis. But again it's basically an unfalsifiable fiction, backed up with almost nothing in the way of empirical evidence.

Surowiecki says that "in the long run volatility is a very bad thing, because it makes ordinary investors less inclined to trust markets". Which is true largely because the financial press insists on reading far too much into short-term stock-market moves.

The path of the stock market is naturally bumpy, especially in down markets. If financial journalists in general, and the talking heads on CNBC in particular, were a bit more sanguine about daily volatility, then maybe ordinary investors wouldn't be worried. But there seems to be an insatiable demand for news about what the stock market is doing today, complete with accompanying narratives about how a 30-point decline in the S&P 500 is evidence of broad-based pessimism about the global economy, or something else along those lines.

The cure for this disease? Don't read, watch, or listen to any stock-market reports. They never contain any useful information, and you're much more likely to mistake noise for signal than you are to learn something substantive.

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This article has 8 comments:

  •  
    <i>Right now we're in a William Goldman market: nobody knows anything.</i>

    And just how does this differs from every other day?
    I mean, other than those pretending they know something.
    2008 Aug 25 09:12 AM | Link | Reply
  •  
    William Goldman is a screenwriter and in Hollywood they don't have a clue what's going on typically. Maybe he meant nobodies like him no anything. There are always people on the inside or somewhere that know something. It's just hard to get to them or find them. Right now the market is so confusing that no one really knows but normally that's not the case.
    2008 Aug 25 09:27 AM | Link | Reply
  •  
    I have read 10-20 words of it,before anyone dares to cite a word about V O L A T I L I T Y please remember that there are good times and bad times,actually as stock market is concerned there is always a bad time and stocks rise only because folks invest,insiders cash on it,in the hard environment like this days,low volatility means the storm is just around the corner.Crash will come when nobody will expect it,not when experts will pretend they nknow about it.Then volatility skyrockets with such a speed that you are 50% off,too late to get out as insiders a first to cash on your long positions.There are people who are for long term,and there are those who cash in before and live happy thereafter.
    Dow Jones 9000 is just around the corner,just wait.
    2008 Aug 25 09:27 AM | Link | Reply
  •  
    If you believe in the mean-variance asset pricing model or any other multi-factor model that includes mean and variance, as most people do, then vol has to be a determinant of stock prices. Period.
    2008 Aug 25 09:37 AM | Link | Reply
  •  
    Volatility correlates 90% or so with average volume. (Trailing 20 days for both etc). Claiming it is bad because it drives people away from markets has a bit of a problem, when it occurs in the first place because lots of people want to trade at once.

    What low volatility correlates with it dull smooth continued trends, beloved of trend followers and long term index holders, who are always long. Level traders, on the other hand, meaning people who have an independent opinion about what stocks are actually worth, benefit from periods of volatility, which give them a chance to enter at attractive prices and occasional to exit at insane ones.
    2008 Aug 25 10:24 AM | Link | Reply
  •  
    Very good advice. In fact, studies (such as this one) shows volatility has little to do with risk. Volatility's impact is more psychological.

    2008 Aug 25 10:52 AM | Link | Reply
  •  
    the best part of this article was the last paragraph.just like handicapping football.talking heads.shark&paul,t... me,has got it right.he or she should be on cnbc,not those overpaid,born with a silver spoon in thier mouth,idiots!again,sha... really makes the most sense out of anyone.
    2008 Aug 25 11:12 AM | Link | Reply
  •  
    JPDD's observation is the most valid. The author should have ended the article with the reference to another's work and the comment that he agrees. In fact, he should have simply added "I agree" to the comment section of Jim's article and spared us his diatribe.
    2008 Aug 26 04:25 PM | Link | Reply
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