Big banks are picking up home-loan market share with the aggressive marketing of rate discounts and fee waivers to borrowers who are refinancing.The latest AFG Mortgage Index, published yesterday, shows a significant increase in the number of borrowers refinancing in June. The big banks captured a higher share of that business.Of 6205 loans written by AFG brokers in June, 39.2 per cent were for refinancing - the highest proportion of loans for refinancing this year. The big bank share of AFG's business rose from 80.4 per cent in May to 82.1 per cent in June. Big bank share has been below 80 per cent only once in the past 12 months.AFG's general manager of sales and operations, Mark Hewitt, said: "We have never seen the major lenders as hungry for business as they are right now."They have some very competitive offers on rates, fees and switching incentives, and people who already have mortgages are seeing the benefits of reviewing their arrangements."