Microcaps aren't the little sibling ofsmall, mid, and large cap funds, but anopportunity to reap high returns. Companiesin a microcap fund generallyhave a market capitalizationof $500 millionor less. Microcaps are veryvolatile, and the shorttermoutlook could bedreary. According to, investing inthese small companies is basically boom orbust. If you're not afraid of the roller coasterride, then microcap funds have thepotential to reward your bravery big time.The recent opening of the Bridgeway Ultra-Small Company Market Fund has advisorsexcited because it is a positive microcapopportunity that is priced lower than mostmicrocap funds, reducing the inherent risk.But experts caution that physician-investorsshouldn't throw large amounts of money atmicrocaps. Although they have been performingwell recently, the hazard of theirinstability is too extreme to bet the farm.