Impact of Six Sigma implementation on stock price performance

There have been many reported successful cases of Six Sigma implementation in the past few years. As stock price performance is one of the realistic criteria for business performance, two studies are presented in this paper in this regard. One is stock prices' reaction on the day when Six Sigma activities were made known publicly, and the other is the long-run stock performance of 'Six Sigma companies'. The abnormal returns on the event day are evaluated in terms of three models, namely mean adjusted, market adjusted and market models. A full sample consists of 20 announcements, and two sub-samples with four announcements and 16 announcements each were analysed. The result shows that the abnormal returns are not significant on the event day. A study on six firms shows that, in the long-run, stock performance of Six Sigma companies did not significantly outperform S&P 500. This analysis of stock price performance would help set a realistic expectation of Six Sigma benefits. It offers an alternative perspective on the impact of Six Sigma on a macro scale, rather than the common project-by-project performance measures such as defect minimization and immediate cost savings.