Finra fines Goldman Sachs (GS -0.3%) $800K for not having properly designed policies to prevent trade-throughs of protected quotes in NMS stocks from November 2008 through August 2011 in connection with its Sigma-X dark pool.
In English, rules generally require trading systems trade at the best-quoted prices or route orders to those quoting the best prices. An investigation found from July 29, 2011 to August 9, 2011 there were more than 395K transactions executed in Sigma-X where the execution "traded through" to an inferior price.
During this time, Goldman was unaware this as happening. Goldman has since returned $1.67M to injured clients.
Previously: NY AG reportedly probing dark pools