Small but significant non-transitory increase in price meaning

A small but significant non-transitory increase in price (SSNIP) describes the standard “hypothetical monopolist” test used in competition law to define the relevant product and geographic market for merger control, abuse of dominance and anticompetitive agreement analyses. It asks whether a hypothetical monopolist of the candidate products in a given area could profitably sustain a small (often 5–10%) price rise for a meaningful period (commonly around a year). If enough customers would switch to substitutes so that the rise would not be profitable, the candidate market is widened to include those substitutes, and the test is repeated. The SSNIP test is not set out in UK or Irish statute, but is embedded in guidance and case law: see the UK Competition and Markets Authority’s market definition and merger assessment guidance and sector regulators’ approaches, and, in Ireland, the CCPC’s practice and the European Commission’s Market Definition Notice. Usage is broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland. In practice, authorities adapt the test for two‑sided or zero‑price markets (using quality or SSNDQ), bidding and differentiated products, and price discrimination. The outcome frames assessments of market power, competitive constraints and potential remedies.