Deal failure usually begins in assumptions made before signing

Make assumptions governable before commitment

Many deal failures begin before signing, when strategic fit is asserted broadly, synergies are counted without operational paths and integration constraints remain implicit. Once price, public narrative and executive sponsorship are committed, weak assumptions become harder to challenge and more expensive to correct.

The deal thesis should be decomposed into claims about customers, cost, capability, timing and behavior. Each claim needs evidence, confidence, value contribution and an owner. Management should identify what would disprove it and which assumptions depend on the same condition, preventing correlated optimism from hiding in separate workstreams.

Synergies require a mechanism and implementation cost. Revenue synergy needs named customers, proposition, sales capacity and timing; cost synergy needs process, decision, dependency and service-risk analysis. Double counting and benefits that require mutually incompatible integration choices should be removed.

Pre-mortems and downside scenarios create permission to challenge momentum. Teams test talent loss, customer reaction, delayed approval, systems incompatibility and leadership overload. Findings should affect price, structure, conditions and the integration plan�not sit in an appendix after approval.

At close, the assumption ledger becomes the value-realization baseline. Owners track evidence, update forecasts and escalate when a thesis weakens. This continuity from diligence to integration turns learning into action and makes early correction possible before sunk cost converts a questionable assumption into a defended strategy.