Fisher Sells Stake of Up to $3 Billion to Advent, Abu Dhabi Fund

Private equity firm Advent International and a unit of the Abu Dhabi Investment Authority are buying a minority stake in billionaire Ken Fisher’s Fisher Investments worth as much as $3 billion.

The transaction, in which the acquirers will invest at least $2.5 billion, values closely held Fisher at $12.75 billion, the money-management firm said Sunday in a statement. The deal is part of Ken Fisher’s estate planning, according to the company, and will let Fisher Investments continue to operate independently.

“While my health is excellent, this transaction with an atypically long holding period for a private equity transaction ...