Wednesday, June 10, 2009


OK. I won't mention the fact that Henry Blodget was charged with securities fraud, and settled for $4m. in penalties and a ban from ever trading again. Oops.

Starting over, he's been worried about "hyperinflation," but he doesn't know what hyperinflation is. That, or he can't do math. By "math" I mean the simple arithmetic involved with the finance "rule of seventy." I'm worried about hype. Anyone with an undergrad B-school degree should know the Rule of 70, which approximates an asset's doubling time (here goods prices). Blodget fears high-end estimates of inflation meaning prices doubling in 10 years. Specifically, Years to double = 70/rate of change. Since exponential growth is not linear (hey, it's exponential in fact!) it's only an approximation, but it's a decent one as they go. So, some very elementary algebra tells us that prices doubling in 10 years means 7% inflation annually. Uncomfortable, but not "hyper." By contrast, hyperinflation is usually reserved for situations like Argentina in the mid-80s (about 650%, or doubling every 39 days) or Weimar Germany (3,000,000%, or doubling every 5 days or so).

To say doubling in 10 years is hyperinflation is simply false. Prices in the US more than doubled between 1973 and 1982, and while it was uncomfortable, it was not "hyper."

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