"Mike has had an enormous impact during his time at the agency, and will leave behind a substantial legacy of accomplishments," said SEC Chairman Christopher Cox.

Since coming to the SEC in 2006, Halloran, 66, assisted in the SEC's management and advised its efforts to promote investor protection, healthy and fair markets, and capital formation. In particular, he played a key role as the Commission strengthened the investor protections under Section 404 of the Sarbanes-Oxley Act while reducing unnecessary costs, especially for smaller companies, through the adoption of Management Guidance on its internal controls assessment and of Public Company Oversight Board Audit Standard No. 5 to replace the prior Audit Standard No. 2 on the internal controls audit.

Prior to joining the SEC's staff, Halloran had a 32-year career at the law firm of Pillsbury Winthrop Shaw Pittman LLP,