The Algorithm Behind Jim Simons's Success

One strategy with enduring success: betting on retracements. About 60 percent of investments that experienced big, sudden price rises or drops would snap back, at least partially, it turned out. Profits from these retracements helped Medallion do especially well in volatile markets when prices lurched, before retracing some of that ground.

in the markets and in life, to be successful one should bet on the upside that comes from a) evolution that leads to productivity improvements, but not so aggressively that b) cycles and bumps along the way knock you out of the game.