"We're looking to have a physical presence in most of the major wealth centers in the United States," Gregory Fleming told Reuters in an interview. Its business now spans 40 offices with over $90 billion under management, growing from three offices and $18 billion in assets in 2018.

Fleming is an industry veteran who previously led Morgan Stanley's wealth and investment management arms. As chief operating officer of Merrill Lynch, he helped steer the Wall Street firm through the financial crisis and its acquisition by Bank of America.

Rockefeller, which currently has about 250 private wealth advisers, aims to increase that to 400-500 in three to five years.

It has already made some senior hires to fuel the expansion. Eric Heaton, former president of U.S. banks at Morgan Stanley, joined Rockefeller this week to advise the CEO on its strategy and growth plans. Rose Lee, previously at Credit Suisse, was hired in July as head of investment solutions to develop and manage products such as investments and securities.

Rockefeller will concentrate its wealth-management efforts in the United States, where it already has a presence in major metropolitan areas, Fleming said. The company plans to open an office in Orlando, Florida and deepen its presence in Charlotte, North Carolina, Austin, Texas and Nashville, Tennessee.

"The opportunity is still significant," Fleming said.

In terms of markets, Rockefeller is advising clients to be cautious through early next year, particularly if the Federal Reserve raises interest rates more aggressively than markets are currently predicting. Given that backdrop, Rockefeller's clients have been buying U.S. Treasuries with nearer-term maturities of two, three and five years to take advantage of rising bond yields.

Investor demand is still firm despite bouts of illiquidity in the $23 trillion U.S. Treasury market, Fleming said.

(Reporting by Saeed Azhar and Lananh Nguyen; Editing by Mark Potter)

By Saeed Azhar and Lananh Nguyen