Explain why an investor might choose each approach along the range from passive to highly active equity management

At the passive end, the case rests on market efficiency, low fees, low turnover, tax efficiency and the arithmetic that average active return before costs is zero. Factor-based or smart-beta approaches sit in the middle: rules-based tilts toward rewarded factors such as value or momentum at lower cost than full active management. Full active management is justified when the client believes the manager has skill that survives fees, when markets are less efficient, or when the client has preferences, such as ESG or tax constraints, that an index cannot meet. The decision should weigh expected alpha against fees and tracking risk. The trap is equating low tracking error with passive management. A closet indexer charges active fees for near-index exposure.