A rollup is a series of acquisitions through which a financial sponsor consolidates ownership. Increasingly, this strategy is shaping economically important markets, but historically, it has escaped antitrust enforcement. We study this phenomenon in the anesthesia industry, site of the first rollup-based antitrust case in US history. First, we identify 18 other rollups that are observationally similar to the litigated ones. Next, we show that rollups consolidate ownership and that prices rise sharply as competing practices are acquired. Last, we estimate a structural bargaining model and simulate counterfactual equilibria under remedies that courts are likely to consider.