When entering a new market, a marketplace must decide whether to build demand (buyers) or supply (sellers/providers) first. Casey Winters treats this as situational rather than a fixed rule — there's no universally correct order — but notes the field has shifted: today roughly 9 out of 10 marketplaces launch supply-first, seeding enough sellers/listings before opening demand-side acquisition. GrubHub itself did not follow this now-dominant pattern originally: it started demand-first (building diner demand before it had full restaurant coverage) and later switched approach.
Relates to Marketplace PMF Takes ~2x Longer Than B2B SaaS PMF (this sequencing choice is part of why marketplace PMF takes longer — each side must be solved, in some order, before the loop closes) and to Core Growth Loop Mapping & Acquisition Grafting.
As of Casey's telling, roughly 9 out of 10 marketplaces launching in a new geography today start supply-first rather than demand-first — a shift from earlier marketplace-building norms. GrubHub itself switched from a demand-first to a supply-first approach for new-market launches, illustrating that the right choice is situational (competitive intensity, ease of signing supply vs. building demand in that specific market) rather than a fixed rule.