By HLPR Online Staff Yesterday, in Halliburton Co. v. Erica P. John Fund, Inc., the Supreme Court, among other holdings, upheld the more than 25-year-old “fraud on the market” theory for securities fraud class actions. Though at first glance this complex case may seem to involve only a very specific and technical distinction, the end result has wide-reaching (and expensive) implications for every large public company involved in U.S. securities markets. Under SEC Rule 10b-5, one of the …