One assignee leads the ranked field with 2,508 records, far ahead of the fifth-place holder at 249 and the tenth at 144. The top five assignees combined hold 28.1% of all 13,035 records in scope, and the top ten hold 34.5%, which means the remaining two-thirds of the field is spread across a long tail of companies and institutes filing only occasionally. This concentration pattern is typical of fields anchored by one or two platform biologics developers alongside many single-application entrants.

Filing activity peaked at 241 records in 2020 and has declined since, falling 43% from 191 records in 2021 to 108 in 2024 — the most recent year that can be treated as a complete comparison point. Figures for 2025 and 2026 are still artificially low because publication typically lags filing by around 18 months, so they should not yet be read as a continuation of the decline. Based on the complete-year data, the honest read is a pullback from a 2020 peak rather than a field in freefall.

C07K (peptides and proteins) and C12N (microorganisms and genetic engineering) each appear in more than seven in ten of the 13,035 records, reflecting how closely purification claims are tied to the biologic being purified. A61K and C12P each cover a little under half of records, and B01D — the class most directly tied to separation-process and gradient-elution hardware — covers only 16.6%. Because records often carry multiple classes, these shares add up to well over 100%, and should be read as coverage rates, not as a breakdown that sums to the whole.