This study investigates the changes in the marginal cost, revenue, and profit efficiencies after a series of deals by US acquiring banks for the period from 1992 to 2007 using the nonparametric data envelopment analysis (DEA) method and the market reaction model. All the efficiency measures show increases in the first two deals but show significant decreases in the next two to three deals and substantial efficiency increases for the last two acquisitions. The efficiency losers are those that engage in just four mergers. Banks that undertake six to seven acquisitions recover their earlier efficiency losses to achieve a net 12.5% cumulative profit efficiency. The results of the market reaction model show that acquirers lose the most by the time they announce their third and fourth deals, 25.8% and 23.9% respectively, while targets gain the most when they acquire their fourth deal, 34.5%. The efficiency dynamics results show consistency with both the managerial hubris theory, where efficiency gains occur in early deals (first and second), and the learning theory where efficiency measures form a U-shape curve. These results show that the theories are complementary rather than contradictory. Moreover, frequent acquirers tend to be highly profitable, but most importantly they are externally attracted to finding targets with specific characteristics like a relatively small size, high percentage of operating assets, and a high cost efficiency.

这项研究使用非参数数据包络分析（DEA）方法和市场反应模型，调查了1992年至2007年美国收单银行进行一系列交易后的边际成本，收入和利润效率的变化。所有效率指标在前两笔交易中均显示出增加，但在接下来的两到三笔交易中则显示出显着下降，而在后两项收购中则显示出显着的效率提高。效率下降者是那些只进行了四次合并的人。进行六到七次收购的银行可以收回先前的效率损失，以实现12.5％的净累积净利润效率。市场反应模型的结果表明，收购方在宣布第三笔和第四笔交易时损失最大，分别为25.8％和23.9％，而目标客户在获得第四笔交易时获得的收益最高，为34.5％。效率动力学结果显示出与管理狂妄自大理论（在早期交易（第一和第二笔交易）中出现效率提升）和学习理论（其中效率度量形成U形曲线）的一致性。这些结果表明，这些理论是互补的，而不是相互矛盾的。此外，经常收购的人往往会获利丰厚，但最重要的是，他们从外部被吸引来寻找具有特定特征的目标，例如相对较小的规模，较高的运营资产百分比和较高的成本效率。以及效率测度形成U形曲线的学习理论。这些结果表明，这些理论是互补的，而不是相互矛盾的。此外，经常收购的人往往会获利丰厚，但最重要的是，他们从外部被吸引来寻找具有特定特征的目标，例如相对较小的规模，较高的运营资产百分比和较高的成本效率。以及效率测度形成U形曲线的学习理论。这些结果表明，这些理论是互补的，而不是相互矛盾的。此外，经常收购的人往往会获利丰厚，但最重要的是，他们从外部被吸引来寻找具有特定特征的目标，例如相对较小的规模，较高的经营资产百分比和较高的成本效率。