Financial terms of the deal were not revealed.
Founded in 1992, the acquired entity currently oversees £300m for its high-net-worth clients and their families.
As part of the deal, PMN partners, advisers, and support team will become part of CBAM.
PMN’s clients would benefit from CBAM’s research capabilities, financial planning offerings and wider investment management services.
The acquisition, which is part of CBAM’s growth strategy, expands the firm’s regional footprint across the Surrey and Hampshire border.
CBAM chief executive Martin Andrew said: “I am delighted to welcome PMN to the CBAM family, an acquisition which further underlines the fact that we are a dynamic and growing business.
“Not only is PMN a highly successful and trusted provider, but crucially, the business has deep cultural synergies with CBAM. Our success is built on our dedication to put clients at the centre of everything we do and PMN share that commitment and focus.”
CBAM, part of British merchant banking group Close Brothers Group, has footprint across Manchester, London, Gatwick, Bristol, Chester, Farnham, Newcastle, the Midlands, Northwich, Glasgow, and Edinburgh.
In September last year, Close Brothers Group reported a decrease in profit, with a rise in impairments amid the Covid-19 crisis.
The firm revealed that its adjusted operating profit in the year to July stood at £144m, a 47% decrease from £270.5m in fiscal 2019.
Profit attributable to shareholders dropped 46% to £109.5m from £201.6m over the period.
In June last year, the group named Adrian Sainsbury as chief executive, succeeding Preben Prebensen.