Three senior partners are exiting Australian big six firm Clayton Utz in the coming months, with two set to join rival firms in the country.

Perth-based energy partner Kevin O'Sullivan is understood to be taking a non-executive directors' role, while the former head of M&A John Elliott will join Norton Rose Fulbright and David Stammers, previously overseeing private equity, will move to Ashurst in Sydney.

Norton Rose's managing partner Wayne Spanner said Elliott was "an outstanding M&A lawyer", and that he expected him to join the firm in the New Year once he has finalised his exit arrangements. 

Ashurst declined to comment any further on Stammers' arrival, but it is understood he is also in the transition process.

The hire is rather timely for the firm, which recently lost two partners from its Sydney M&A team – Ian Williams and Daniels Roberts – to Herbert Smith Freehills.

Speaking to Legal Week about the departures, Clayton Utz chief executive Robert Cutler did not comment on the circumstances, but said the firm was in the process of regenerating its partnership.

"While I wish the departing partners all the best, the bottom line is that they are not part of our future.

"On 1 July we moved to a national practice group structure with 14 leaders… We saw the need to reinvigorate and renew some areas of the business, particularly our corporate practice, and bring through people with fresh ideas and talent."

He added that the firm would look to add to its corporate team in time, concentrating on the promotion of lawyers internally but looking to the market if necessary.

"The timing is uncertain," he said. "I don't expect a significant increase in corporate activity next year."

Clayton Utz is among a number of big Australian firms to have downsized in recent years, dropping by 31 partners and 218 lawyers between September 2014 and September 2009.

Since July, it has also made approximately 20 lawyers redundant across Sydney and Melbourne, and also some national roles.

However, it has also recruited four new partners laterally in the last year across real estate, IP and employment, and made four vertical partner appointments effective 1 January 2014.

Cutler said the focus now was more on regenerating than downsizing. He previously talked of adding in infrastructure and regulatory, as well as banking and finance.

"I do not have any pre-determined size or shape of the firm, but we need to be profitable… generational change is at the heart of that."