This paper investigates whether the quality of mergers and acquisitions（M&A）is higher when acquiring firms and target firms share the same external analysts. Our intuition is that the acquisition process often involves considerable uncertainty, including information asymmetry between bidders and targets regarding their operations, financial health, corporate culture, risks and prospects as well as uncertainty related to post-acquisition operational synergies. This uncertainty would negatively impact M&A performance by reducing managers’ ability to identify the most profitable investment projects, and make an evaluation objectively. We argue that when an acquirer and a target share common analysts, these analysts can help to reduce uncertainty along several dimensions.　　On the one hand, analysts can communicate with managers of target firms to obtain some private information through conformance call, site visit and investor meeting. At the same time, analysts can also acquire some information related to industry prospects and macro-economic environment using their relations with peer firms, other research departments and government institutions. Combining with the extra information, managers of bidders can screen the profitable investment target and make an appropriate evaluation for the target, which necessitates to make a high quality M&A investment. On the other hand, comparing to other investors in the capital market, analysts have the advantage in interpreting target firms’ complex information about accounting accruals and research development. Moreover, with the help of analysts, managers can have an insight into accounting policy, accounting choice and corporate strategy plan of the target. In this sense, information interpretation advantages of analysts would reduce the information asymmetry between bidders and targets as well as uncertainty about resources synergies after the acquisition. Above-mentioned reasoning suggests that common analysts can improve M&A performance.　　However, a study examining whether common analysts are beneficial to M&A performance is subject to the endogeneity problem. For example, certain types of firms may purposely seek out analysts of target firms because these firms need the knowledge and evaluation that analysts accumulate from targets（the " self-selection” problem）. In order to address the endogeneity problem, we exploit a natural experiment in which brokers’ going public results in an external shock to common analysts. Following Bertrand and Mullainathan（2003）, we employ a difference-in-differences approach to estimate the effect on M&A performance. The results show that there is a positive effect of common analysts on M&A performance, and the effect is much stronger for firms not sharing common directors and common auditors, for firms with fewer similarities to targets, and for firms without M&A experiences before. We also find the higher M&A performance can be attributed to investment project profitability rather than lower premium.　　The conclusions of this paper provide the enlightenment to understand the effect of information intermediaries on corporate financial policies in general, and M&A quality in particular. First, confronting with serious information asymmetry and uncertainty, managers can communicate with common analysts to obtain some information in M&A activities. Due to the information advantage in obtaining private information and interpreting public information, common analysts contribute to shaping high-quality M&A decisions and improving M&A performance. Second, regulators in the financial market can further improve the disclosure quality of corporate information, which can reduce the information processing cost for analysts, facilitate the information to transfer from targets to acquiring firms, and eventually improve the efficiency of resource allocation.