All 31 staff at Inverness-based Highland will be retained, although the company will be rebranded as Capital at the end of the year. Tom Flockhart, founder of Edinburgh's Capital, said the deal was supported by Royal Bank of Scotland and is part of a plan to grow turnover to £30m by the end of 2015.
Capital's most recent annual accounts, for calendar year 2011, show turnover of £14.5 million and pre-tax profit of £1.2m.
Abbreviated accounts for Highland show a retained profit in the 12 months to May 31, 2012, of almost £227,000.
Capital also has operations in Glasgow, Dundee, Aberdeen and Shetland.