Mix-and-match divestitures and merger harm

We consider the effects of a merger combined with a divestiture that mixes and matches the assets of the two pre-merger suppliers into one higher-cost and one lower-cost post-merger supplier. Such mix-and-match transactions leave the number of suppliers in a market unchanged but, as we show, can be procompetitive or anticompetitive depending on whether buyers are powerful and on the extent of outside competition. A powerful buyer can benefit from a divestiture that creates a lower-cost supplier, even if it causes the second-lowest cost to increase. In contrast, a buyer without power is always harmed by a weakening of the competitive constraint on the lowest-cost supplier.