National Australia Bank boss Cameron Clyne said an important part of the rationale for seeking to acquire the Australian and New Zealand businesses of Axa Asia Pacific was the complementary nature of wealth management and business banking.NAB is Australia's biggest business banker and if its $6.43 a share bid for Axa is successful it will be the country's biggest wealth management company.Clyne said: "What we see is cross-sell from our business bank into wealth - small businesses looking at their superannuation and business owners coming to the private bank. It differentiates the bank."NAB yesterday sought to trump AMP's offer for Axa AP by offering shareholders the option of $6.43 a share in cash or $1.59 in cash and 0.1745 NAB shares for each Axa AP share.The $6.43 cash offer represents a 50 per cent premium to Axa's closing share price on November 6, the last trading day before AMP launched its bid.Axa's independent directors yesterday endorsed the NAB bid and rejected AMP's latest offer, citing the higher value of the NAB offer (the implied value of the AMP offer is $6.22 a share) and the greater certainty of an all-cash alternative.There remains talk of a competing bid from another bank. The Herald Sun reported that advisers to ANZ were in contact with Axa.One unusual feature of the NAB bid is that it is proposing to sell Axa's Asian business to Axa AP's majority shareholder Axa SA, but it cannot negotiate with Axa SA until February 6 when an exclusive agreement between Axa SA and AMP ends. NAB's offer is conditional upon Axa SA agreeing to proceed with the acquisition of the Asian businesses.If the deal goes ahead it will be NAB's third wealth management acquisition in a year. This year it bought the Australian operations of the life company Aviva and the JB Were private client business.It has also bought the mortgage management business of Challenger Financial Group.Clyne said he was confident his management team had the capacity to handle another acquisition. "It is a good time because we are making decisions around structures, strategies, resources and infrastructure. With Aviva we are progressing well. We are ahead of plan."A combined NAB/MLC and Axa would be number one in retail superannuation, with a 25 per cent market share; number one in retirement income products, number one in retail managed funds and number one in individual risk.The combined group would have about 3,200 salaried or aligned planners - more than double its nearest rival AMP. Clyne is convinced that scale will be critical to success in wealth management because of the strong push by government to bring down costs and rationalise parts of the industry.NAB's financial case for the Axa takeover seems to be stretched. The bank yesterday refereed to $210 million in cost savings over five years and revenue gains of only $50 million, with the latter a tiny amount given the combined revenue base of the targetted business and NAB's existing MLC, JB Were and Aviva businesses.These modest amounts and