Conjecture over the sale of a stake or even all of Kiwibank may build once more, following the re-election of the National Party at the general election in New Zealand on Saturday.The sale of several state-owned utilities is part of the platform of the Government, but this is the extent of the formal privatisation commitments. The incumbent Prime Minister, John Key, said a number of times during the election campaign that Kiwibank would not be sold, a stance that may not rule out the sale of new shares to external investors.The New Zealand Government has voiced its reticence in the past over supporting the bank. For example, the Finance Minister, Bill English, said 18 months ago that Kiwibank had reached a size where it needed either a government guarantee or "an awful lot of capital".For the time being, Kiwibank's capital position is satisfactory. It had a tier-one capital ratio of nine per cent at the end of June 2011. This was down from 9.8 per cent in 2010, but is a higher ratio than it has had over preceding years.Steady growth in the bank's market share, however, may test its capital ratios beyond the planning horizon envisaged by the board of both the bank and its direct owner, New Zealand Post.Forecasting the capital needs of the bank is becoming more complex in the context both of the transition to the local variant of the Basel III rules and of a Government unlikely to show much interest in tipping in capital (or foregoing dividends) from its NZ Post business in order to sustain the growth of Kiwibank.At September 2011, Kiwibank's market share of home loans was 6.5 per cent, up from 2.5 per cent in September 2011.Its home loan portfolio of NZ$11 billion is funded by NZ$8 billion of deposits and NZ$3 billion of wholesale liabilities.NZ Post has invested NZ$310 million in Kiwibank. There are also NZ$150 million in non-voting preference shares that were sold to external investors in early 2010.Taking into account retained earnings, net assets were around NZ$630 million at September 2011.The bank's Australian-owned major rivals have long complained that the bank acts in a non-commercial manner.If the bank's latest quarterly profit, released on Friday, is any guide, Kiwibank's return on equity is around 12 per cent and its return on assets is around 0.5 per cent. (Data for the 2011 financial year is less representative given the effect of the Canterbury earthquake on the bank's results). Profits of this order don't appear to have restrained those of its larger rivals, however.Research by the Reserve Bank of New Zealand, published in June, found that "the return on equity in the New Zealand banking system appears to have been very high by OECD standards."