As promised, the staffs of the Securities and Exchange Commission and the Commodity Futures Trading Commission have issued a report detailing the preliminary findings of their review of the May 6 flash crash.

The 151-page report says there's currently no evidence that the events, when the markets suddenly plunged more than 5 percent in a matter of minutes, and then quickly bounced back, were triggered by "fat finger" errors, computer hacking, or terrorist activity.

Rather, the staffs are continuing their investigation, focusing on six main working hypotheses and findings:

(1) possible linkage between the decline in the prices of stock index products and simultaneous and subsequent waves of selling in individual securities, and the extent to which activity in one market may have led the others;

(2) a severe mismatch in liquidity, possibly exacerbated by the withdrawal of liquidity by electronic market makers and the use of market orders;

(3) the extent to which the liquidity mismatch may have been exacerbated by disparate trading conventions among various exchanges that slowed trading in one venue, while it continued normally in another;

(4) the need to examine the use of "stub quotes" designed to technically meet a requirement to provide a "two sided quote" but are at such low or high prices that they are not intended to be executed;

(5) the use of market orders, stop loss market orders, and stop loss limit orders that, coupled with sharp price declines, might have contributed to market instability and a temporary breakdown in orderly trading; and

(6) the impact on Exchange Traded Funds, which suffered a disproportionate number of broken trades relative to other securities.

The report is intended to inform the newly created joint SEC-CFTC Advisory Committee on Emerging Regulatory Issues, which will meet May 24 to conduct a review of the disruption and make recommendations related to market structure issues that may have contributed to the volatility.

The committee, led by SEC Chair Mary Schapiro and CFTC Chair Gary Gensler and comprised of market practitioners, former regulators, and academics, was established to develop recommendations on emerging and ongoing issues relating to both agencies.

The committee's formation was among the 20 recommendations of a harmonization report issued by the two agencies last October following a two-day joint meeting held in September. The harmonization efforts are in response to a June 2009 Obama administration white paper calling for the agencies to recommend legislative and regulatory actions to address key differences in their regulatory schemes.

Meanwhile the SEC is seeking comment on proposed rules filed by the exchanges (here and here) and FINRA (here) in response to the May 6 market disruption that would pause trading in certain individual stocks if the price moves 10 percent or more in a five-minute period.