Effective Nov. 3, Mr. Oleksiuk will leave BlackRock for a new role in the corporate governance world. The memo did not disclose where he is going beyond that it will "not (be) at an asset manager."
"He plans to tell us more about the specifics when the time is right," the memo continued.
Michelle Edkins, global head of investment stewardship at BlackRock, will assume the role on an interim basis while the firm seeks a permanent replacement.
Mr. Oleksiuk was head of Americas at BlackRock's investment stewardship group since October 2013.
BlackRock reported $5.977 trillion in assets under management as of Sept. 30.