Tom, Rothbard recounts Mises’s comment about a stock market being incompatible with socialism, as I note here. Rothbard wrote: One time I asked Professor von Mises, the great expert on the economics of socialism, at what point on this spectrum of statism would he designate a country as “socialist” or not. At that time, I wasn’t sure that any definite criterion existed to make that sort of clear-cut judgment. And so I was pleasantly surprised at the clarity and decisiveness of Mises’s answer. “A stock market,” he answered promptly. “A stock market is crucial to the existence of capitalism and … Continue reading re: The Communist Manifesto

I can’t recall where the story comes from, but Ludwig von Mises was reportedly asked once how to distinguish between a capitalist and a socialist economy in light of the fact that there is so much interventionism in “capitalist” economies. His answer was that the defining characteristic of capitalism was private capital markets.