Echo Street Capital Management, the money manager founded by Greg Poole, is returning outside capital to fund investors, according to an email it sent to clients.

“I have decided to return outside capital to partners in the Echo Street funds,” the firm told customers in a message seen by Bloomberg News. “My decision to return capital is entirely personal. It is a bittersweet one as I am going to miss this relationship tremendously.”

A second client confirmed the message’s contents. Echo Street’s portfolio manager, George Panos, plans to launch a standalone, market-neutral fund, it said.

Reached by phone, Panos had no immediate comment and referred inquiries to the firm’s general counsel, who didn’t immediately respond.

Poole, who started his career at Goldman Sachs Group Inc., founded Echo Street in 2002 at age 28 with less than $10 million in assets under management, according to the firm’s website. The money manager had roughly $11 billion at the end of October, according to a person with knowledge of the matter, asking not to be identified discussing confidential communications.

The firm’s Select fund is liquid, and capital will be returned “quickly,” the email said. The Select Plus and New World funds have less than 3% of private-investment exposure and will maintain that until they achieve “future liquidity events.”

The email cited the “poor” history of failed attempts by other firms to pass leadership from founders to a new generation. “Echo Street’s transition, were it to happen, would be exposed to the risks revealed by similar transitions that have already occurred.”

(Updates with background on firm, additional information from email from fifth paragraph.)