Citadel Securities LLC has hired Stephen Luparello as general counsel, according to company spokesman Zia Ahmed.

Luparello will start in May at the market-making firm after most recently working as director for the division of trading and markets at the U.S. Securities and Exchange Commission.

At the SEC, Luparello developed the SEC's equity market structure advisory committee. As Citadel's first-ever general counsel, he will be responsible for all legal matters related to the company.

Citadel Securities operates across a variety of asset classes and conducts about 37% of U.S. retail equities trading volume, according to Ahmed.