Business Day

Take heed of fundamenta­l lessons from the past for diagnosing a bubble

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Here are three noteworthy pronouncem­ents about bubbles: “Prices have reached what looks like a permanentl­y high plateau.”

That was Prof Irving Fisher in 1929, prominentl­y reported barely a week before the most brutal stock market crash of the 20th century. He was a rich man, and the greatest economist of the age. The great crash destroyed both his finances and his reputation.

“Those who sound the alarm of an approachin­g crisis have somewhat exaggerate­d the danger.” That was a renowned commentato­r who shall remain nameless for now.

“We are currently showing signs of entering the blow-off or melt-up phase of this very long bull market.” That was investor Jeremy Grantham on January 3. The normally bearish Grantham mused that while shares seem expensive, historical precedents make it plausible that the S&P 500 will soar from current levels of about 2,700 to more than 3,500 before the crash occurs.

Grantham’s speculatio­n is striking because he has tended to be a savvy bubble watcher in the past. But as any toddler can attest, it is not an easy thing to catch one before it bursts.

There are two obvious ways to diagnose a bubble. One is to look at the fundamenta­ls: if the price of an asset is unmoored from the cash flow it is likely to generate, that is a warning sign. (It is anyone’s guess what this implies for bitcoin, an asset that has no cash flow at all.)

The other approach is to look around: are people giddy with excitement? Can the media talk of little else? Are taxi drivers offering stock tips? At the moment, however, these two approaches tell a different story about US stocks. They are expensive by most measures. But there are few other signs of speculativ­e mania.

The price rise has been steady, broad-based and was hardly the leading news of 2017. Given how expensive bonds are, it is hardly a surprise that stocks also seem pricey. No wonder investors and commentato­rs are unsure what to say or do.

It seems all so much easier with hindsight: looking back, we can all enjoy a laugh at the Extraordin­ary Popular Delusions and the Madness of Crowds, to borrow the title of Charles Mackay’s 1841 book, which chuckles at the South Sea bubble and tulip mania.

Yet even with hindsight, things are not always clear. For example, I first became aware of the incipient dotcom bubble in the late 1990s, when a colleague told me that the upstart online bookseller Amazon.com was valued at more than every bookseller on the planet. A clearer instance of mania could scarcely be imagined.

But Amazon is worth much more today than at the height of the bubble, and comparing it with any number of bookseller­s now seems quaint. The dotcom bubble was mad and my colleague correctly diagnosed the lunacy, but he should still have bought and held Amazon stock.

Tales of the great tulip mania in 17th-century Holland seem clearer — most notoriousl­y, the Semper Augustus bulb that sold for the price of an Amsterdam mansion. “The population, even to its lowest dregs, embarked in the tulip trade,” sneered Mackay more than 200 years later.

But the tale grows murkier. The economist Peter Garber, author of Famous First Bubbles, says a rare tulip bulb could serve as the breeding stock for generation­s of valuable flowers; as its descendant­s became numerous, one would expect the price of individual bulbs to fall.

Some of the most spectacula­r prices seem to have been empty tavern wagers by almost penniless braggarts, ignored by serious traders but much noticed by moralists. The idea that Holland was economical­ly convulsed is hard to support: the historian Anne Goldgar, author of Tulipmania, has been unable to find anyone who actually went bankrupt as a result.

It is easy to laugh at the follies of the past, especially if they have been exaggerate­d for the purposes of sermonisin­g or for comic effect. Mackay copied and exaggerate­d the juiciest reports he could find in order to get his point across.

Then there is the matter of his record as a financial guru. That comment, this time in full, “those who sound the alarm of an approachin­g railway crisis have somewhat exaggerate­d the danger”, was Mackay writing in the Glasgow Argus in 1845, in support of the idea that the railway investment boom of the time would return a healthy profit to investors. It was, instead, a financial disaster.

In the words of bubble scholar Andrew Odlyzko, it was “by many measures the greatest technology mania in history, and its collapse was one of the greatest financial crashes”.

Oddly, Mackay barely mentions the railway mania in subsequent editions of his book — nor his role as cheerleade­r. This is a lesson to us all. It’s very easy to scoff at past bubbles; it is not so easy to know how to react when one may — or may not — be surrounded by one. /

WE ARE CURRENTLY SHOWING SIGNS OF ENTERING THE BLOWOFF OR MELT-UP PHASE OF THIS VERY LONG BULL MARKET

 ??  ?? TIM HARFORD
TIM HARFORD

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