BOK Financial Corporation, the bank holding company for the Bank of Oklahoma, participated in one of the largest merger and acquisitions deals in the relatively quiet third quarter of 2012, buying The Milestone Group, a wealth management firm with more than $1.3 million in assets under management.

Overall, the quarter was the slowest of the year in terms of the number of deals and total assets exchanged through mergers and acquisitions in the financial advisory industry, according to Pershing Advisor Solutions’ “Real Deal” third-quarter update. Seven deals were completed, down from eight in each of the first two quarters. The transactions targeted retail-focused RIA firms that collectively held $6 billion in assets under management, considerably less than the $24 billion exchanged in the second quarter and less than half the assets exchanged in the first quarter. That said, the median level of AUM involved in a deal was $574 million, up from $521 million exchanged by the typical firm acquired or merged in the previous quarter, according to the Pershing update.

The BOK Financial acquisition was one of three involving target firms with assets greater than $1 billion. The two other large buyers were Virtus Investment Partners, which purchased Rampart Investment Management and its approximately $1.4 billion in AUM, and Mariner Wealth Advisors, which purchased a majority interest in the wealth management division of Orizon Investment Counsel, adding approximately $3.8 billion to its AUM.