Marc Gary, the general counsel of the giant financial services company Fidelity Investments, said Thursday that he will leave the company on May 1 to become executive vice chancellor and chief operating officer of the Jewish Theological Seminary in New York City.

Gary told CorpCounsel.com that he was drawn to “the unique opportunity to dedicate the next stage of my professional life to an institution—JTS—whose mission and vision inspire me as well as untold numbers of others, both within my faith community and outside of it.”

But he admitted he’ll miss being a general counsel. “I will particularly miss the challenge of addressing difficult legal issues infused with significant public policy implications” while working with innovative people both within the legal department and in management.

Gary said he is also sorry to leave law interest groups in which he has played leadership roles, including Equal Justice Works, the Lawyers Committee for Civil Rights Under Law, the Pro bono Institute, and Greater Boston Legal Services. But he “hopes to stay involved in some fashion” with as many as possible.

Despite those misgivings, he said it’s an honor to be joining “an institution renowned for its unsurpassed scholarship, its dedication to strengthening Jewish communities and securing the Jewish future, and its focus on personal quests for lives of purpose and meaning.”

Starting July 1, Gary said his new role will allow him to “apply all I have learned as a member of senior management at two major companies known for their operational excellence.”

Gary joined Boston-based Fidelity as GC in 2007. Prior to that, he was associate general counsel and then GC at BellSouth Corporation for seven years. He left when BellSouth merged with AT&T Inc.

Previously, Gary was in private practice with Arent Fox from 1977 to 1980, then with what is now Mayer Brown as a partner from 1981 to 2000. He took a two-year leave of absence to join the U.S. Office of Independent Counsel, but returned to the law firm in 1992.

Headquartered in Boston, Fidelity employs 39,000 people with several regional centers across the United States. It is not immediately known who will replace Gary.

Besides bringing “a true passion” to JTS, Gary said he hopes to also bring a strategic approach, an ability to motivate a diverse group of employees, and a commitment to excellence. He also hopes to find time to write and teach legal subjects.

David Stern, executive director of the public service legal group Equal Justice Works, said Gary is his hero. Gary was scheduled to become the next chairman of EJW, “so we obviously saw him as an extraordinary leader,” Stern said.

Stern described Gary as a passionate and dedicated leader who brought pragmatic sense as well as vision to his work. He thinks the move from Fidelity to JTS makes Gary “a living example of what this organization is all about—people following their passion and doing something that is rewarding, not necessarily financially but to overall happiness.”

Gary knows he will be facing more than just legal issues at JTS. Among them, he said he feels the pluralism and secularism of American society both undergird the country’s strength and present unique challenges to Judaism in terms of assimilation and the struggle for relevance.

“The fundamental question is: What are the unique contributions Judaism will make to individual lives and North American society as a whole in the 21st century?” he said. “I firmly believe that the Jewish Theological Seminary. . . is the institution best situated to answer that question and meet those challenges.”