ANZ chief executive Shayne Elliott might be set to unveil an earnings surprise at the bank's full year profit announcement later this month after the release of data showing his bank is eclipsing major rivals in the high margin business lending market.The latest edition of APRA's monthly statistics shows that ANZ was the only major bank to grow overall lending to business borrowers in the five months to the end of August.According to the regulator's numbers, ANZ grew lending to financial institutions and non-financial businesses by A$5 billion to $131 billion during the opening five months of its second half reporting period.The growth boosted ANZ's market share of the  business lending market by 0.4 per cent to 14.4 per cent.ANZ's performance was particularly meritorious given the overall market expanded by only $11.5 billion to $907 billion during the period.The increase in ANZ's business loan book equated to 43 per cent of total system growth.National Australia Bank remains a market leader in the lending to Australian businesses, but lost market share in the second half of its financial year.NAB had $189 billion lent out to financial institutions and other businesses on 31 August - no change from its end of March position.However, due to system growth, NAB's market share declined 0.3 per cent to 20.8 per cent.CBA, the country's second largest business lender suffered a 0.1 per cent dip in market share to 17.8 per cent. At the end of August it was sitting on a loan book of $162 billion.Westpac was the biggest loser.Since the end of March, Westpac's business loan book has reduced by $5.4 billion to $152 billion.The sharp fall meant that its market share was crunched to 16.7 per cent - 0.8 per cent lower than in March.The new data is significant because it clearly indicates that the three market leaders are losing ground to ANZ and a host of other lenders including regional and foreign banks.The banks posting the biggest gains during the period included the Agricultural Bank of China, which has increased lending by almost $1 billion since the end of March.The gains made by non-bank lenders appear to be exerting a disproportionate impact on the lending mix of regional banks.Bank of Queensland also expanded its lending to financial institutions and other types of businesses by more than $1 billion over the five month period.The big issue for banking analysts in the lead up to the banking sector's reporting season is whether ANZ and BoQ have gained market share in business lending on the back aggressive pricing strategies.If so, the net revenue upside for each bank's shareholders could be negligible given the direct impact of discounting on net interest margins.