Growth in lenders' mortgage and business portfolios has weakened over the past few months, while the personal loan market has recorded its weakest figures in four years.According to the latest Reserve Bank lending data, lenders' mortgage balances increased by 0.5 per cent in August, compared with the previous month, and by 6.5 per cent over the 12 months to August.The annual growth rate in mortgage balances has fallen from a peak of 7.5 per cent in November last year.Owner-occupier mortgage balances increased 0.5 per cent in August, compared with the previous month, and by 7.6 per cent over the 12 months to August.Investor mortgage balances grew by 0.5 per cent month-on-month and by 4.6 per cent over 12 months.Business loan balance grew by just 0.1 per cent in August, compared with the previous month, and by 5.7 per cent over the 12 months to August.The annual growth rate in business loan balances has fallen from a peak of 7.3 per cent in April.Personal lending balances continued their decline, with a month-on-month fall of 0.1 per cent and a fall of 1.2 per cent over 12 months. The annual fall in personal credit balances is the biggest drop since 2012.