Analysis of the spread risk involved in corporate bond investing allows one to estimate the fair value of corporate sector spreads. In particular, a strategy that takes into account the volatility of a particular credit sector's spread relative to that of the overall market can produce total returns in excess of those on the overall market, irrespective of time horizon, starting point and rebalancing frequency. The results suggest that active sector rotation can yield profit opportunities. The strategy is more efficient than simply investing in a specific sector or constant mix of sectors. It is also superior to a sector-rotation strategy based on the excess of current over historical spreads, without regard to risk.