Have you ever ridden in a car with worn-out shock absorbers? Every bump is jarring, every corner stomach churning, and every red light is an excuse to assume the brace position. Owning an undiversified portfolio can sometimes trigger similar reactions. In a motor vehicle, the suspension system keeps the tires in contact with the road and provides a smooth ride for passengers by offsetting the forces of gravity, propulsion and inertia. You can drive a car with a broken suspension system, but it will be an extremely uncomfortable ride and the vehicle will be much harder to control, particularly in difficult conditions. Throw in the risk of a breakdown or running off the road altogether and there is a real chance you may not reach your destination. In the world of investments, a similarly bumpy and unpredictable ride can await those with concentrated and undiversified portfolios or those who constantly tinker with their allocations based on a short-term rough patch in the markets. Of course, everyone feels ...