Robert Jackson Jr., the senior Democrat on the Securities and Exchange Commission, announced Thursday that he is leaving Feb. 14.
"I will always be proud to have served alongside my fellow commissioners, Chairman (Jay) Clayton, and especially the commission's staff, who dedicate their careers to protecting ordinary investors and give hard-working American families the chance to build a better future," Mr. Jackson said in a statement.
A commission staff member from Mr. Jackson's office, Caroline Crenshaw, is expected to be nominated by the White House to fill the position. Ms. Crenshaw also worked with former commissioner Kara Stein and served as a judge advocate in the Army JAG Corps.
Tyler Gellasch, executive director of Healthy Markets, an investor-focused non-profit organization in Washington whose members include many pension funds, said in an email that "while Crenshaw may be a new name for many, SEC followers know she's been a key aide to both Commissioners Stein and Jackson, so if she replaces him, we would expect a similarly strong investor advocate."
Mr. Jackson was appointed to the SEC by President Trump and confirmed by the Senate in January 2018. He was the first Democrat appointed to the SEC by Mr. Trump, who was legally obligated to appoint two non-Republican commissioners to balance the current three Republican members, including Chairman Jay Clayton.
Mr. Jackson's term expired in June but he had up to 18 months to stay on while a replacement could be confirmed by the Senate.
Mr. Jackson will be returning to New York University School of Law, where he has overseen research into many of the market issues that come before the commission.
During his SEC tenure, he has been an outspoken advocate for shareholders and a critic of corporate practices such as stock buybacks, as well as fee practices of exchanges and the SEC's best interest standard.
"Jackson's commitment to investors, as well as his efforts to work across ideological lines, made him an extremely effective commissioner. I hope to see him return to Washington in another capacity at some point and expect he would be on a lot of 'short lists' for any future Democratic administration," said Mr. Gellasch, who called the commissioner's wit and enthusiasm "a double shot of espresso in the often bloodless world of regulatory acronyms and buzzwords."
Former Commissioner Stein in an emailed statement called Mr. Jackson "a relentless advocate for making sure our modern markets remain the fairest and most efficient in the world. I hope our country will be fortunate enough to have him engage in public service again in the future."