This study examines whether recent mergers between small and midsize accounting firms influence competition by increasing the number of firms that can compete with larger rivals in the U.S. public company audit market. I find that in-market mergers generate efficiencies that are reflected in a post-merger reduction in audit hours but not in reduced audit quality. For both in-market and out-of-market mergers, clients switching to post-merger firms are more likely to be accelerated filers and are significantly larger in terms of several proxies for size and complexity. Lastly, I find that an increase in market-level merger activity is associated with lower profitability of Big 4 firms operating in the same market but only in the smaller client segment. These findings suggest that recent mergers have actually increased competition in some segments of the audit market despite already high concentration and concerns about a lack of sufficient competition.

本研究探讨近期中小型会计师事务所之间的合并是否会通过增加能够与美国上市公司审计市场上较大竞争对手竞争的公司数量来影响竞争。我发现市场内合并所产生的效率体现在合并后审计时间的减少，而不是审计质量的下降。对于市场内和市场外合并，转向合并后公司的客户更有可能成为加速申报者，并且在规模和复杂性的几个指标方面要大得多。最后，我发现市场层面合并活动的增加与在同一市场但仅在较小客户群中运营的四大公司的盈利能力较低有关。这些发现表明，最近的合并实际上有所增加尽管审计市场的集中度已经很高，但审计市场的某些领域仍然存在竞争，而且人们担心缺乏充分的竞争。