With seven companies joining the test group during the past three months, including Alcoa this week, more than 40 companies are now participating in the SEC's voluntary interactive data filing program. The test group remains open to new participants.

Interactive data refers to financial information provided using XBRL or any other computer software language that labels companies' financial data with codes from standard lists called "taxonomies" so that investors and analysts can more easily locate and analyze desired information in a public company's financial statements.

"The continued positive feedback from our enthusiastic group of test filers means that interactive disclosure is well on its way to becoming reality," said SEC Chairman Christopher Cox. "Investors in the future will have instant, user-friendly access to company disclosures that are far more accurate than anything that is possible with today's EDGAR."

Cox said that he expects to make a separate announcement next week about another "major milestone being reached in the introduction of interactive financial reporting."