When a newly-launched drug achieves early prescriber interest, specialty pharmacies build initial inventory to meet anticipated demand. This produces an inflated revenue quarter (the "stocking quarter") followed by a dramatic apparent decline as distributors draw down inventory rather than order more. The resulting YoY comparisons against both the inflated and deflated quarters remain distorted for 4+ quarters and make the growth trajectory appear both stronger and weaker than the underlying commercial momentum actually warrants. Analysts must identify the stocking event, flag the affected quarters, and use a "clean commercial baseline" starting only after inventory normalization completes.
When analyzing a recently-launched specialty pharma (first 4-8 quarters): (1) Identify any quarter where sequential revenue exceeds expected launch ramp by >2x — this is likely a stocking event. (2) Flag the subsequent reversal quarter as normalization, not deceleration. (3) Avoid citing YoY growth rates from quarters distorted by the stocking event; use QoQ momentum or sequential trend from the normalization quarter forward. (4) The "clean commercial baseline" typically establishes 3-4 quarters after the stocking reversal — this is where durable growth rates become readable. This pattern is distinct from M&A comp cliffs (different mechanism, same analytical challenge: separating reported from underlying).