Oct. 27 (Bloomberg) -- Goldman Sachs Group Inc., the most profitable securities firm, defended for U.S. regulators dark pools, short-selling, high-frequency trading and other market practices that have been criticized by lawmakers. Goldman told the Securities and Exchange Commission that computer-driven trading and an increase in stock transactions that occur off public exchanges has reduced consumer costs, increased competition and brought more liquidity to markets. âThe investing community (especially retail) has benefited from the evolving market structure and industry competition,â Goldman Sachs said in a summary of the 55-page report submitted to the agency. The SEC is under pressure from lawmakers such as Democratic U.S. Senators Charles Schumer and Ted Kaufman to rein in some of the fastest-growing segments of U.S. markets. Kaufman in August asked the commission to review seven practices including high- frequency trading, saying investor confidence may be eroded. Executives from New York-based Goldman met with staff for Commissioner Luis Aguilar last month and sent a copy of the report, according to an Oct. 22 notice on the SECâs Web site. Trading on dark pools, off-exchange platforms that donât display public quotes, has more than quadrupled to 9.4 percent of all U.S. equity volume in the past three years, according to Tabb Group LLC. High-frequency traders, whose computer programs buy and sell shares up to 1,000 times faster than the blink of an eye, account for about 46 percent of daily volume. Goldman, which operates the Sigma X dark pool, in the document identified five âmythsâ associated with the platforms. The bank said itâs a misconception that dark pools create a âtwo-tiered market structureâ to the detriment of retail investors and that platforms that donât publicly display orders are a new phenomenon. SEC Proposals The SEC proposed rules Oct. 21 that would require dark pools to publicly report some bids once they handle 0.25 percent of a stockâs average daily volume. The electronic networks usually shut down trading in a security when they approach the existing 5 percent limit. Goldman, in its report, said âsmall changes and clarificationsâ could benefit current rules regulating dark pools. The Goldman executives who met with Aguilarâs staff Sept. 24 included Managing Directors Paul Russo, William Conley and C. Annette Kelton, according to the notice. http://www.bloomberg.com/apps/news?pid=20601087&sid=ax4InQgscKws Hum, who has been appointed COO of SEC lately ?