Sharpe's development of Markowitz's "underlying factor" model could still be seen as operations research rather than economics: it was published in Management Science (Sharpe 1963) rather than in an economics journal. At root, though, Sharpe was an economist, and Armen Alchian had taught him microeconomics-the foundational part of the discipline that studies how production and consumption decisions by rational firms and individuals shape market prices, giving rise to equilibrium in competitive markets.

Donald MacKenzie, An Engine, Not a Camera, loc. 234