McKinsey Alpha
An informal but persistent finding: companies that announce major McKinsey engagements underperform the index over the following 3 years.
Multiple academic analyses and investigative accounts have documented a recurring pattern: S&P 500 companies that announce major McKinsey & Company engagements tend to underperform the broader index over the subsequent 36 months. The causality is disputed — this could reflect selection effects (companies already in trouble hire consultants), the disruptive cost of large engagements, implementation failures, or the quality of strategic advice delivered. What is not disputed is the statistical pattern itself. McKinsey, for its part, has not published a peer-reviewed rebuttal.
Informal meta-analysis drawing from academic literature on consulting firm performance impact, Duff McDonald's 'The Firm' (2013), and business press reporting on major McKinsey client trajectories. Based on average stock performance of companies disclosing significant McKinsey engagements versus S&P 500 benchmark, measured over a 36-month trailing window post-announcement. Not a formal academic study; treat as directional.