As regulators continue to investigate last Thursday's extreme market volatility, the Investment Industry Regulatory Organization of Canada (IIROC) has announced that it has re-priced or cancelled various trades occurring during the market slide. Various U.S. markets have also announced that they would cancel trades (see for example announcements from NYSE Arca and NASDAQ). Meanwhile, the Securities and Exchange Commission (SEC) announced yesterday that it has met with the leaders of the Financial Industry Regulatory Authority, NASDAQ, BATS, Direct Edge, ISE and the CBOE, and that all parties have agreed on a structural framework for strengthening circuit breakers and handling erroneous trades.

Today, the SEC and Commodity Futures Trading Commission announced the formation of a joint committee to address "emerging regulatory issues", with the first item on the committee's agenda being a review of last Thursday's market events. Meanwhile, SEC Chairman Mary Schapiro testified before the Financial Services Committee's Subcommittee on Capital Markets, Insurance and Government Sponsored Enterprises this afternoon to summarize the events of May 6, provide an overview of the current market structure and discuss various regulatory tools to be considered "in determining how best to maintain fair and orderly financial markets and to prevent severe market disruptions in the future."