The equity valuation of many companies has a calculable, 'fair value' range. Stock prices frequently over-shoot and under-shoot this range, creating an opportunity to achieve attractive, risk-adjusted returns for when prices revert to their fair value range.
Companies change slowly. Stock prices change very rapidly. Stock exposures should be actively monitored and rebalanced accordingly.
Investors benefit from downside protection in their equity exposure. Downside protection is an outcome of both quality stock selection and constant portfolio management within strict risk controls.