We document that public firms participate more than private firms as buyers and sellers of assets in merger waves and their participation is affected more by credit spreads and aggregate market valuation. Public firm acquisitions realize higher gains in productivity, particularly for on-the-wave acquisitions and when the acquirer's stock is liquid and highly valued. Our results are not driven solely by public firms' better access to capital. Using productivity data from early in the firm's life, we find that better private firms subsequently select to become public. Initial size and productivity predict asset purchases and sales 10 and more years later.