<p>We study how introducing private-label brands (PLs) affects retail prices and profits, accounting for assortment adjustments of national brands (NBs). We employ an event-study framework and scanner data on the US beef market. When a PL is added to the low-priced market segment, we find that retail stores further differentiate NBs from the PL and remove same-segment NBs. When a PL is added to the high-priced segment, however, NB assortment changes are limited. PL introduction and PL-driven NB assortment changes impose small price effects on NB, but strongly cannibalize NB demand and steer consumers toward PLs, likely increasing store profits.</p>