The U.S. Securities and Exchange Commission is examining the exposure of stock exchanges, brokerages and other Wall Street firms to cyber-attacks that have been called a threat to financial stability.

The SEC is holding a roundtable discussion of those risks in Washington today as it weighs a new rule proposal asking whether stock exchanges should be required to tell members about breaches of critical systems. More than half of exchanges surveyed globally in 2012 said they experienced a cyber-attack, while 67 percent of U.S. exchanges said a hacker tried to penetrate their systems.

The agency also will probe how companies are disclosing cyberthreats to investors in public filings. Businesses including Target Corp., from which hackers stole payment-card data for millions of shoppers in December, are required to disclose such threats when the information would affect an investor’s willingness to own the company’s shares.

Mandatory Disclosures

Companies aren’t required by the SEC to disclose all risks from cyber-attacks, though the regulator routinely reviews how such threats and incidents are described in annual reports. Some lawmakers, including Senator Jay Rockefeller, a West Virginia Democrat, have asked the agency to consider making the disclosures mandatory.

“This is information every investor has a right to know,” Rockefeller said in a statement yesterday. “Routinely providing this information should be a regular part of practicing business in the era of ‘big data.’”

The Financial Stability Oversight Council, a group of regulators led by the Treasury secretary, said in its 2013 annual report that successful cyber-attacks could pose a threat to the stability of financial markets. Among exchanges, 89 percent said cybercrime should be considered a systemic risk, according to a 2012 International Organization of Securities Commissions report.

Finra Priority

The SEC and the Financial Industry Regulatory Authority, which oversees broker-dealers, identified cybersecurity as a priority for compliance examinations. Finra said in January it would ask about 20 of its member firms how they manage and defend against the threat of cyber-attacks.

Criminal hacking cost financial services companies, on average, about $18.8 million in 2013, according to a study by the Ponemon Institute, a research and consulting firm. The report estimated an average cost for brokerages of $19 million and $21.9 million for investment advisers.

Hackers targeting broker-dealers may seek intellectual property such as trading algorithms or the source code of trading systems, said Richard Bejtlich, chief security strategist at FireEye Inc., a Milipitas, California-based information-security consultant. Manipulation of critical data systems probably poses the greatest risk to Wall Street companies whose buy-and-sell decisions and order routing are increasingly automated.

Breach Reports

Under a rule proposed last year, exchanges would be required to promptly disclose to their broker-dealer members any breaches of critical systems. Exchanges could withhold the information if they believed release of the data would do further harm or undermine an investigation of the intrusion. The SEC expects to advance the rule this year, White said today.

“If you can start changing the data that you have access to, that can potentially undermine the integrity of the system and that is where people get pretty nervous,” Bejtlich said in a phone interview.

Panelists scheduled to speak at today’s roundtable include representatives of Bank of America Corp., BATS Global Markets Inc., the Chicago Board Options Exchange, Nasdaq OMX Group Inc. and Wells Fargo Advisers LLC. The Treasury Department’s Cyrus Amir-Mokri, assistant secretary for financial institutions, and White House cybersecurity adviser Ari Schwartz also will speak, according to an SEC announcement.