National Australia Bank is the one bank that has acquired meaningful extra market share in the home loan market over the last couple of years, with other major banks largely consolidating their positions after the windfall generated by the financial crisis of 2008.But monthly APRA data shows NAB still remains well behind its "natural" market share, if the relevant measure is the peak in home-loan market share of banking system assets of 17 per cent it recorded back in 2003.Australian Prudential Regulation Authority data shows that since late 2009 NAB has added A$39 billion in new home loans in Australia, a little more than Commonwealth Bank and a little less than Westpac. This gives it a market share only two-thirds the size of the industry's largest suppliers of housing finance.NAB's October 2011 market share of 15.7 per cent is a gain of 1.6 percentage points since its low point in market share, reported in April 2010. On the other hand, it needs to recover another 1.6 percentage points to return to its early 2000s market share.While NAB is gaining ground, market leader Commonwealth Bank is still tolerating a slow erosion of its lead.The APRA figures show that CBA has lost a few basis points in market share each month since April 2010.CBA's market share of home loans, as a percentage of loans provided by all banks, was 27.8 per cent at the end of October.Had the bank maintained its April 2010 market share of 28.6 per cent, it would have increased its home loans by $32 billion rather than $23 billion. Instead, CBA has conceded to other providers a market share equal to that of AMP Bank.