There's always a silver lining, right?

A statement on Friday afternoon by Securities and Exchange Commission Chairman Mary Schapiro described an apparent trading error by Knight Capital Group on Aug. 1 as “unacceptable” and the “type of event that can raise concerns for investors about our nation's equity markets."

The positive spin? Schapiro noted that “several of the measures [the SEC] instituted following the Flash Crash [of May 2010] helped to limit its impact.”

Recently-adopted circuit breakers halted trading on individual stocks that experienced significant price fluctuations, and “clearly defined rules” guided the exchanges in determining which trades could be broken, she said.

“Existing rules make it clear that when broker-dealers with access to our markets use computers to trade, trade fast, or trade frequently, they must check those systems to ensure they are operating properly,” Schapiro said. “We will consider whether such compliance measures were followed in this case.”

A full investigation is underway, she said, adding that her staff will accelerate efforts to propose a rule that requires exchanges and other market centers to “have specific programs in place to ensure the capacity and integrity of their systems.”

In a statement Thursday, Knight said problems at the open of trading at the NYSE were related to the installation of new trading software and a glitch that sent out a flurry of erroneous orders.

The fallout isn't pretty. Knight traded out of its entire erroneous trade position, an unwinding that gave it a realized pre-tax loss of approximately $440 million. The company is “actively pursuing its strategic and financing alternatives,” which is more than just a good idea given that losses exceeded the $365 million in cash it reported having as of June 30.