Commercial real estate brokerage Cassidy Turley will merge with DTZ Group as part of a deal expected to close by year’s end.

Washington, D.C.-based Cassidy Turley has 4,000 employees at 60 offices in U.S. markets, including Boston. The new owners are backed by investors TPG, PAG Asia Capital and Ontario Teachers’ Pension Plan, which has agreed to acquire DTZ Investment Holdings after it combines its operations with Cassidy Turley by Oct. 31. Together, the companies would have more than 28,200 employees and $2.9 billion in revenues.

Cassidy Turley CEO Joseph Stettinius Jr. will become chief executive of the Americas and Tod Lickerman will remain global CEO of DTZ.

Terms of the transaction were not disclosed. The Wall Street Journal, citing sources familiar with the deal, said it was believed to be worth $500 million to $600 million, including $75 million in debt.

In addition to the consortium, former CBRE Group CEO Brett White is investing in the acquisition and will join the board of directors, the companies said.

The companies said the merger will result in "minimal overlap" of leadership and markets in the U.S. Chicago-based DTZ has extensive operations in Europe and Asia, which will complement Cassidy Turley’s U.S. focus.

During 2013, Cassidy Turley brokered $25.8 billion in transactions.

Cassidy Turley’s Boston office at One International Place is headed by Regional Managing Principal Joseph P. Fallon. It currently employs 61 people, spokeswoman Maureen Wheeler said.