Abstract: Taking into account the characteristics of GEM ownership structure and selecting 50 representative M & A events of the companies listed on the GEM as the research sample， the factor analysis method was used to measure the overall M & A performance of the sample and the multiple linear regression method was adopted to examine the impact of the ownership structure of the companies listed on the GEM upon the M & A performance. The results indicated that on the whole the M & A performance of the companies listed on the GEM didnt improve much and there existed a negative correlation between ownership concentration and M & A performance. Thus， Chinas listed companies should reasonably change their ownership structure， set up the ownership checks and balances mechanism， reduce the financial risks， and strengthen the effective integration after the merger.

Key words: GEM (growth enterprise market), M & A performance, ownership structure, factor analysis