Robert Shiller | Phil's Stock World

time machine An Obvious Approach?

Always and everywhere the market timing argument resurfaces in multifarious forms. The idea is simple: sell high and buy low: what could be more obvious? Well, there’s a problem. It’s not necessarily insurmountable but it’s definitely a bit tricky.

You may need a time machine to implement the concept successfully.

Market Timing

The idea behind market timing is easy to state. Sell stocks when they’re high and buy them when they’re low. It’s the basic idea the lies behind all investment in stocks so it’s hard to see why anyone should object. The difficulty lies in the impossibility of implementing the technique accurately in the timescales generally envisaged. Which, to be precise, tends to mean any timescale you can envisage at all. Mostly we have no idea ahead of time whether any given stock has peaked or troughed. Most guesses – let’s not dignify these with the term “forecast” – turn out to be wrong.

Unfortunately the idea is seductive and apparently easy to implement, in hindsight. Looking back everything seems so obvious that the untrained human brain finds it almost impossible to believe that the future isn’t equally predictable.

Buy and Hold

A recent study from the CFA shows that markets go up twice as much as they go down. Their recommendation, if you have cash to invest, is to invest everything now: the research shows that this will maximise your returns over an investment lifetime.

However, this is a pretty unnerving suggestion: had you thrown your money into the market back in the middle of 2006 you’d be sitting on a very nasty loss. Of course, you’d have been appallingly unlucky to get your timing that wrong, but inevitably some people did and the fact that the odds were against them doing so will be no consolation. The alternative suggested by the authors is to feed your money into the markets gradually – averaging your costs. This is a form of insurance, ensuring that you don’t put all your cash in at the market top or, of course, the market bottom.

However, the research also shows that there’s a limit to the value of averaging. After eighteen months there’s no discernable benefit to spreading the timescale of your investments. The vast majority of the benefit comes

Robert Shiller of the infamous Case-Shiller index has a particularly interesting piece in the NYT. Instead of hammering on numbers he takes a look at the psychology of home buyers and sellers and why that might

affect home prices for some time to come.

Shiller examines the behavioral biases that lead people to “irrationally” hold onto houses during a period or declining values. The concluding paragraphs are thought provoking:

For this reason, not all economists agree that home price declines are really predictable. Ray Fair, my colleague at Yale, for one, warns that any trend up or down may suddenly be reversed if there is an economic “regime change” — a shift big enough to make people change their thinking.

But market changes that big don’t occur every day. And when they do, there is a coordination problem: people won’t all change their views about homeownership at once. Some will focus on recent price declines, which may seem to belie any improvement in the economy, reinforcing negative attitudes about the housing market.

Even if there is a quick end to the recession, the housing market’s poor performance may linger. After the last home price boom, which ended about the time of the 1990-91 recession, home prices did not start moving upward, even incrementally, until 1997.

I say it’s thought provoking because when you look at the recent frenzy in the lower priced end of the housing markets it’s hard to come up with a theory that squares with Shiller’s ideas. Unless you are of the opinion that the drastic decline in prices constitutes an economic “regime change.” Certainly, there hasn’t been any fundamental shift at all in the general economy that has prevailed in this sudden shift from a buyers to sellers market. So what might be driving it?

The only plausible theory I can come up with is that the buyers perceived an exceptional opportunity to purchase housing at favorable prices. Did they do so on the assumption that prices were about to begin a march back? Is the meme that you can’t lose money long term buying real estate so firmly ingrained that no amount of empirical evidence to the contrary will diminish it or are they simply grabbing an opportunity to buy shelter?

What

Stocks for the

Source: FRED.

Blue line: Nominal value of S&P500 stock index, January 1980 to December 2009. Red line: value as of January 2000. Data source: Robert Shiller.

Green line: Real value (in 2009 dollars) of earnings on the S&P500, January 1980 to December 2009. Dashed blue line: arithmetic average of green line for the preceding 10 years. Data source: Robert Shiller.

Cyclically adjusted P/E over the last century. Blue line: Ratio of real value (in 2009 dollars) of S&P composite index to the arithmetic average value of real earnings over

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