After a string of high-profile departures, Morgan Stanley announced Wednesday a significant hiring. The new executive comes from a law firm, however, not a rival brokerage.

The embattled brokerage firm has brought aboard Shearman & Sterling senior partner David Heleniak, who will join the firm as a vice chairman, managing director and member of the firm’s management committee, reporting to chairman and chief executive officer Philip Purcell. Prior to becoming senior partner at Shearman & Sterling, Heleniak, headed the firm’s M&A group.

Morgan Stanley says that in his new role, he will have a broad mandate encompassing work at the senior-most levels with clients, regulators and other key constituencies around the world, as well as with the firm’s senior management team on issues of policy and direction, external and government affairs, and legal and regulatory matters.

“We are very proud and happy that David is joining Morgan Stanley,” said Purcell, “We have known and worked with him on some of the largest, most complex and industry-defining transactions of our time, and we have long admired his intellect, his commitment to excellence and his dedication to his clients. For these reasons, and for many others, we know he will fit in very well at Morgan Stanley.”

Among those deals, Heleniak represented Citicorp in its merger with Travelers Group, Sandoz in its merger with Ciba-Geigy to form Novartis, Alex.Brown in its merger with Bankers Trust, Viacom in its acquisitions of Paramount and Blockbuster, and the special committee of the board of Molson on its merger with Coors.

Heleniak joined Shearman & Sterling in 1974. From 1977 to 1979, he served in the U.S. Treasury. From 1987 to 1993 he also served as president of The MacDowell Colony, Inc., a not-for-profit artist colony located in New Hampshire. He is also a member of the boards of directors of the New York City Partnership, The Council for the United States and Italy, The Legal Aid Society, The Japan Society and the New York City Ballet, a member of the Council on Foreign Relations and a corporate partner of In Motion, a pro bono organization providing legal assistance to indigent women.