Fidelity Investments has named Abigail "Abby" Johnson chief executive, according to an internal memo sent by the mutual fund firm Monday and viewed by The Wall Street Journal.

Johnson, 52, will take over the position from her father, Edward "Ned" Johnson III, who is 84 years old and has been CEO since 1977. Ned Johnson, whose father founded the company in 1946, will remain chairman, according to the memo.