WASHINGTON/NEW YORK, Sept 8 (Reuters) - Regulators probing the stock market "flash crash" last May still have not uncovered a single cause but will point to stub quotes and other previously identified issues as having exacerbated the market's dramatic drop, according to sources familiar with the probe.
Another source said the U.S. Securities and Exchange Commission is still asking about a "smoking gun" that might explain the May 6 crash, when the Dow Jones industrial average plunged some 700 points before sharply recovering, all in about 20 minutes.
Regulators are soon due to issue a follow-on report on the crash, which rattled investors worldwide and exposed flaws in the high-speed electronic marketplace.
So far, the report by market regulators does not contain a lot of new information and is expected to repeat earlier findings that a number of events caused the crash, two sources said. The sources requested anonymity because regulators are still collecting data and finalizing the report. (Reporting by Jonathan Spicer and Rachelle Younglai; editing by John Wallace)