Effective corporate governance helps build vibrant and efficient capital markets. There was a remarkable transformation in the disclosure practices of Indian companies since the legislation of corporate governance norms through Clause 49 of the Listing Agreement in the year 2000. This in turn improved both the quantity and quality of information available for an investor in the capital market. Ideally, this should result in 'informationally-efficient' stock markets. This article investigates the consequences of governance regulations and the impact of information diffusion on Indian capital market efficiency using GARCH (1, 1). The corporate governance legislation through Clause 49 had a significant impact on the Indian stock market volatility. There has been substantial reduction in market volatility in the post-governance act period. However, there was no evidence substantiating that additional news improved the informational efficiency of the markets. In fact, the additional information resulted in greater volatility persistence. © 2013 Macmillan Publishers Ltd.