Case: Account-mapping a 200-account target list with one partner produced a 31% co-sell win rate vs 12% solo

Case: Account-mapping a 200-account target list with one partner produced a 31% co-sell win rate vs 12% solo

A vertical SaaS vendor selling into healthcare systems ran a structured account-mapping exercise with a single systems-integrator partner: overlaying their 200-account target list against the partner's existing relationships to find warm, co-sellable accounts.

The overlap analysis surfaced 47 accounts where the partner had an active relationship the vendor lacked. These became a dedicated co-sell motion — joint account plans, partner-led intros, shared opportunity reviews.

Measured over 12 months against the vendor's solo motion into comparable accounts:

— Co-sell win rate: 31% on the 47 mapped accounts.
— Solo win rate on comparable target accounts: 12%.
— Average deal size on co-sold deals ran 1.4x larger, attributed to the partner's existing footprint enabling broader initial scope.

The selection bias here is unavoidable and the vendor flags it: the 47 accounts were chosen because the partner already had a relationship. Those accounts were warmer by construction. The honest comparison isn't co-sell-vs-solo in general but 'partner-relationship accounts vs cold accounts,' which inflates the apparent co-sell effect.

Even discounting for that, the pattern matches account-mapping research from the partner-tech space (Crossbeam, Reveal): mapped overlap accounts convert at multiples of cold-account rates, primarily because the partner relationship substitutes for trust-building that would otherwise consume the early cycle.

The trade-off: account mapping requires sharing customer lists, which raises competitive-sensitivity and data-governance concerns. They used a privacy-preserving overlap tool that revealed only intersections, never full lists.

Open questions: How much of the 31% is the co-sell motion versus the pre-existing warmth of those specific accounts? A randomized co-sell-vs-solo split within the 47 would isolate it.