AS waves of M&A have swept over Nigeria business organization,conglomerate companies have been caught in the middle of the turbulence. There is no known study that has investigated these significant events in the conglomerate companies quoted on the Nigerian Stock Exchange. Built upon the financial theories and methodology,the performance and investment returns to the share holders of conglomerate companies that have carried out M&A transactions were assessed. The study findings,which were drawn from an analysis of four conglomerate companies out of eight conglomerate companies quoted on the Nigeria Stock Exchange indicate the performance of companies that carried out M&A was significant as measured by correlation relationship of net total assets in relation to the turnover, profit before tax, profit after tax,profit margin, earnings per share and return on capital employed. Whereas the market performance of the selected companies in relation to their average raw returns was used to determined the investment returns to the shareholders shows a weak positive correlation of 3.1% which indicates that investment returns to shareholders of companies is insignificant (t-0.191 & p-0.850)