Burton G. Malkiel, Fred D. Arditti, Manak C. Gupta, Session Topic: Recognizing the Impact of Growth: Discussion, The Journal of Finance, Vol. 30, No. 2, Papers and Proceedings of the Thirty-Third Annual Meeting of the American Finance Association, San Francisco, California, December 28-30, 1974 (May, 1975), pp. 548-555

Michael J. Brennan, Willard T. Carleton, Stewart C. Myers, Session Topic: Financial Models of Regulated Firms: Discussion, The Journal of Finance, Vol. 30, No. 2, Papers and Proceedings of the Thirty-Third Annual Meeting of the American Finance Association, San Francisco, California, December 28-30, 1974 (May, 1975), pp. 446-450

A substantive body of equity-market academic research documents an extensive range of costs arising from the SEC’s October 2000 adoption of strictures on selective disclosure and insider trading; suggesting an unusual outcome, specifically, an increase in informed trading. We investigate the efficacy of the SEC’s regulations by examining informed trading in an attractive setting for exploiting private information; the options market. Using data on the S&P 1500 industrial firms, our analysis indicates that about 38% of firms exhibited symptoms of informed option trading prior to regulatory intervention. After regulatory intervention, we observe that only 19% of firms show symptoms of informed trading. In additional testing of ADR firms – explicitly exempt from complying with Reg FD, we find no evidence of a change in informed option trading from pre- to post-regulation; suggesting that the SEC’s strictures on US firms led a to a significant reduction in informed option trading. Notably, our proxies for large shareholder and financial analyst access are associated with the largest decreases in informed option trading. In developing a unique measure of informed trading based on option market data, we provide evidence on the efficacy of security regulation in limiting informed trading.