The article presents a study dedicated to identifying the factors influencing the efficiency of transactions on mergers and acquisitions. It suggests 5 hypotheses on the results of transactions on mergers and acquisitions on the Russian market. A regressive model of efficiency measurement was developed based on the short-term efficiency model. The Thomson Reuters Advanced Analytics databases were used as an information base for finding transactions and constructing equations. Yahoo Finance was used as the data source on the companies’ stock quotations during a week before and after the transaction. Based on data analysis, 30 high-standard merger and acquisition transactions were reported; they were performed in seven different sectors with various concentration measures. Based on the mentioned hypotheses, a theoretical model for calculating the transaction efficiency values was offered. The following factors were discovered: the larger transaction value, the greater merger and acquisition transaction efficiency for the buying company. Collaboration with an independent outside advisor of a major audit company will have a positive social return as well. In order to account for sector specifics, e.g., concentration ratios, average values of merger and acquisition transaction efficiency were  calculated (by sectors). There is a case study on the efficiency measurement of the transaction between the two leading mineral fertilizer producers (Uralkaliy JSC and Silvinit JSC, which was declared in December, 2010). The key factors, which influenced the transaction’s short-term efficiency, were defined. Recommendations for increasing merger and acquisition transaction efficiency were developed for Russian companies.