Big Three (management consultancies)
The Big Three management consultancies, also known as MBB, are McKinsey & Company, Boston Consulting Group (BCG), and Bain & Company. They are widely regarded as the most prestigious strategy firms in the world, known for their rigorous analysis and advice to large, influential companies. They recruit very selectively from top undergraduate programs and MBA schools, and also hire senior experts from industry.
Starting out as pure strategy firms, the MBB firms have expanded to offer a broader set of services, including operating-model design, performance improvement, M&A due diligence, human capital, and digital/AI transformation.
A quick look at their history: McKinsey was founded in 1926 in Chicago by James O. McKinsey. BCG began in 1963 with Bruce Henderson and grew from two consultants to thousands across many offices. Bain was founded in 1973 by Bill Bain; it helped launch private equity investing through Bain Capital, and Bridgespan, a non-profit consultancy, split from Bain in the early 2000s.
The firms are praised for delivering real impact but have faced criticism over ethical concerns. A notable example is McKinsey’s work with Purdue Pharma to boost sales of OxyContin, a case linked to the U.S. opioid crisis.
They remain among the largest strategy firms by revenue. Bain is especially known for its strong culture and was named the #1 place to work on Glassdoor in 2025. Careers at MBB are highly sought after, with very low acceptance rates.
This page was last edited on 2 February 2026, at 05:01 (CET).