AS a rule in life, as soon as someone starts talking about "intangibles", it is time to be suspicious. A mediocre athlete who is worth his place on the team because of his intangible qualities should arouse scepticism. So should any company selling the intangible quality of their assets.

This is a serious problem because the stock market is increasingly populated by intangible companies. Some 40 per cent of public stocks quoted in the United States have negative tangible book value, meaning that their tangible assets are not worth enough to repay all their debt. Two decades ago, this was only true of 15 per cent of companies, according to Vincent Deluard of INTL FCStone Inc, who has carried out intensive research on the subject.

Such companies sound dreadful. In tangible, material terms their share certificates are not even worth the paper they are written on. And yet, incredibly, a "negative-value" fund, composed of the shares of companies with negative tangible book value, would have beaten the main US stock market, represented by the Russell 3000 Index, by 24 per cent over the last 20 years. That outperformance has almost all happened since the financial crisis - before that, the negative-value fund had roughly tracked the benchmark.

This seems nuts. Capitalists without capital are ruling capitalism. It also sounds very scary. The US stock market has pleasantly surprised many people by going on a decade-long rally, but the success of the negative-value companies makes it sound as though that success is entirely built on sand. So what can explain this? Mr Deluard offers two popular explanations:

To strengthen the notion that this is about the de-materialisation of the economy, international comparisons show an east-west divide. In the United Kingdom and the eurozone, 30 per cent of companies have negative net value, while in China, Japan and South Korea barely any companies do. Increasingly, Asia has become the factory for the world, populated with financially (and physically) sturdy companies, while the US and to a lesser extent of Europe are becoming spirits in an immaterial world.

In practice, these two explanations are not mutually exclusive. Tangible assets are less important, particularly when it is so cheap to finance the purchase of competing financial assets; and it is true that financial engineers have worked on maximising earnings per share rather than broader measures of profit.

That is clear from the growing discrepancy between the reported earnings of companies in the S&P 500 Index, which kept rising until very recently, and the profits drawn up by the National Income and Profit Account (NIPA) as part of calculating gross domestic product (GDP), which have been stagnant for years.

There is perhaps one further explanation that needs to be mentioned:

The Bank of International Settlements is worried by the rise of zombie companies, which it has been charting for years. It defines a zombie broadly as a company whose interest coverage ratio (ICR) has been less than one (meaning that it does not produce enough cash to pay its debt payments) for at least three consecutive years and if it is at least 10 years old. This excludes small companies and start-ups that are borrowing heavily to fund a plan for future growth. On this basis, some 12 per cent of companies in the US are now zombies. Less than 2 per cent were in this state three decades ago.

This should be of concern because it suggests that capitalism's process of creative destruction is not working. Zombie companies tend to be less productive than others, so their survival may well be a part of the explanation for the low productivity that has bedevilled the West since the financial crisis.

All of these factors, I believe, are at work in the rise of negative-value companies. In all cases, a return to higher interest rates would bring this group great difficulties. Zombies and companies hollowed out by private equity would face an existential crisis, while we would see how well the new immaterial giants could cope once money had a higher price. That in turn might help to explain why last year's moderate rise in interest rates by the Federal Reserve was greeted with a horror, and a market sell-off that prompted a U-turn (and this year's rally). Investors evidently did not want to discover what would happen to negative-value companies once interest rates returned to normal.

Now, the hope must be that they can postpone that moment indefinitely. If that cannot happen, then the time will come when we will all learn a lot more about the true value of intangibles. WP