The big margin lenders, CommSec and ANZ Investment Lending, strengthened their positions last year, according to the latest Investment Trends report on the market.Investment Trends said that CommSec increased its share of new margin loans from 37 per cent to 39 per cent last year, while ANZ Investment Lending increased its share from 16 per cent to 17 per cent.NAB's share was nine per cent. Investment Trends did not release market share figures for other margin lenders.According to Reserve Bank figures, the number of margin loan accounts fell two per cent to 144,000 in the 12 months to September, while the value of outstanding balances rose 3.6 per cent to $12.3 billion. Investment Trends estimates that the number of active users of margin loan accounts was 67,000 at the end of last year - down 4.3 per cent over 12 months.Investment Trends head of research Recep Peker said as many as 96,000 investors were considering using margin lending because of its value in helping diversify a portfolio and its tax benefits.He said one of the industry's strong trends over the past few years had been the shift in the customer base from advised borrowers to self-directed borrowers."Self-directed margin loans now comprise 45 per cent of outstanding debt, up from 34 per cent in 2010," Peker said.Leveraged Equities had the highest rating for overall client satisfaction, followed by CommSec and BT Margin Lending (which had the strongest growth in its satisfaction rating).