Fundamental and quantitative investing used to be the hedge-fund versions of oil and water: They didn’t mix. Those in the fundamental camp do analysis the old-fashioned way, evaluating investments based on research and instinct, with humans calling the shots. Quantitative money managers turn to sophisticated computer algorithms that search mountains of data for hidden signals and then make rapid-fire investment decisions. A middle ground has recently emerged: "quantamental" investing, a merger of computer and human-based decision making. It’s not yet clear whether the whole is more than the sum of its parts.