Post Keynesianism in Practice

From the FT the other day:

That Facebook is worth $50bn or Twitter $10bn, is recounted as fact. ... But there are still precious few numbers to analyse and business models are no more proved than for dotcoms a decade ago.

To illustrate the ridiculousness of trying to value these things consider LinkedIn. Its S-1 registration statement (with US regulators) provides rudimentary financial statements from which to model the company. Revenues, operating costs, capital expenditure and depreciation and amortisation schedules are available for the past five years. It is then a hop to forecast earnings before interest, tax, depreciation and amortisation and, thus, future free cash flows. Discount these cash flows (made easier because there is no debt) and you’ve got a valuation.

But who on earth knows what forecasts to make? Private secondary markets supposedly value LinkedIn at $2.5bn-$3bn. To arrive at the bottom of that range requires sales to expand 60, 50 then 40 per cent over the next three years, before tailing off to a terminal growth rate of 3 per cent in 2019. Ebitda as a proportion of revenues has to double to 20 per cent and stay there. ... If sales growth tapers off faster than expected or if systems spending becomes a bottomless pit, you can halve that valuation for starters. But what if LinkedIn’s platform easily copes with millions of new members? Double ebitda margins to 40 per cent and a $5bn company is easily within reach. Who knows? No wonder it’s easier to simply quote the same price tag as everyone else.

Fundamental or Knightian uncertainty tends to get treated as something airy-fairy, as part of the philosophy-of penumbra rather than economics per se. But as this example shows, it's unavoidable in plenty of practical questions. Mainstream models avoid dealing with the problem by assuming that the true probability distribution of all possible future events is always known. But in the real world of business people aren't so silly. As the man says:

The outstanding fact is the extreme precariousness of the basis of knowledge on which our estimates of prospective yield have to be made. Our knowledge of the factors which will govern the yield of an investment some years hence is usually very slight and often negligible. If we speak frankly, we have to admit that our basis of knowledge for estimating the yield ten years hence of a railway, a copper mine, a textile factory, the goodwill of a patent medicine, an Atlantic liner, a building in the City of London amounts to little and sometimes to nothing; or even five years hence. In fact, those who seriously attempt to make any such estimate are often so much in the minority that their behaviour does not govern the market. ...

Investment based on genuine long-term expectation is so difficult to-day as to be scarcely practicable. He who attempts it must surely lead much more laborious days and run greater risks than he who tries to guess better than the crowd how the crowd will behave... It needs more intelligence to defeat the forces of time and our ignorance of the future than to beat the gun.

Economists might not believe in Keynes any more. But business journalists certainly seem to!