One region, one confirmed assessment
Oliver Wyman does not publish a global online assessment. It publishes one, for Brazil and Mexico, and the spec is precise: 26 questions in 50 minutes, covering four areas the firm names directly as critical reasoning, problem solving, data sufficiency and integrated reasoning. Instructions arrive by email the day before.
That page is also the only place Oliver Wyman publishes a full funnel: application, online assessment, a 15-minute fit conversation in English with no case component, then two rounds of two case interviews each, four in total. The firm states that "all stages are evaluative and eliminatory," and that candidates rejected at the fit stage must wait a year before reapplying.
Elsewhere the picture is different. The South Africa Consultant Accelerator Program describes three interviews and no online assessment. The global interview preparation page, the UK and Ireland page and the Asia Pacific page mention no test at all. No Oliver Wyman page names an assessment vendor: prep sites often attribute the test to Cappfinity (formerly Koru), but that attribution is not confirmed by any Oliver Wyman page.
If your invitation email describes something other than the format above, the email is right and the internet is guessing.
The six-step case method the firm asks you to use
Oliver Wyman is unusually prescriptive about how it wants a case handled, and publishes the sequence itself: pinpoint the issue by asking clarifying questions, break it down, pick an approach and state your assumptions, analyse the issues, use numbers, then make a recommendation.
It also distinguishes two interview types clearly. Conversational interviews cover your background, interests and goals. Case interviews are described as "an interactive exercise in analytical thinking," often built on real client challenges.
The best free resource any firm publishes
Six full practice cases sit on oliverwyman.com with model answers revealed step by step, including the assumptions and the arithmetic: Poseidon Water Park, Supermarket Pharmacy, Dairy Farm, Oil and Gas Price Strategy, Urban Grocers and Autism Digital Device. Each is labelled with a difficulty level. The firm also links its own virtual job simulations, covering integrated consulting and financial services climate work.
Working through all six with the revealed answers closed is the highest-value preparation available for this firm, and it is free.
Timing
Oliver Wyman recruits into Marsh McLennan's application portal and publishes events rather than deadlines. As of late August 2026, UK and Ireland entry-level and 2027 summer roles are listed as opening soon, with a run of university events from early September through October. The OWn Your Future European programme ran in April 2026 and that cycle has closed.
Worth noting for context: the headline figures on Oliver Wyman's about page, roughly 95,000 colleagues across 130 countries, describe Marsh McLennan as a whole. Oliver Wyman does not publish its own headcount or office count.
Official sources: Interview preparation · Latin America recruiting · Entry level · Consultant Accelerator Program · UK and Ireland recruiting