Monday, November 28, 2016

Bogle did the math wrong

Michael Regan interviewed Vanguard Group founder Jack Bogle for Bloomberg Markets last week, and I suppose it would be tempting to be like "so, Jack Bogle, index funds are pretty good, right?" "Yup, pretty good." "Thanks for your time." I mean, it is pretty straightforward. And there's a little of that -- "the math is the math, and I think the mathematics are inarguable," says Bogle -- but they also get into some of the more abstruse critiques of indexing.

I heard his comment, and no I did not go read his thesis.  But it is a pretty good guess he did a continuous versions on the math, which implies he assume Ito's calculus is always good, a bad mistake.  His math will be horribly wrong when the generational helicopter flies.

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