One of the highlights in NAB's interim result was the strong growth in trading income in the institutional division, nabCapital.Trading income rose 98 per cent as clients sought risk management services to help them deal with volatile markets.This helped push nabCapital's revenue up more than 30 per cent to $1.5 billion.The strong trading income offset a fall in fees and commissions, adverse fair value movements on SCDO risk mitigation trades, credit value adjustments on derivative portfolio and an overlay in respect of the conduit related assets.The bank does not expect that trading income will be as strong in the second half now that financial markets are starting to settle.