The recent resurgence in trading activity has not only breathed life back into regional stock markets but also the businesses that handle market transactions, as demand for custodian and clearing services picks up again. 'When money comes into Asia, transaction volumes and also equity values will go up,' said Carmen Ling, Citigroup's managing director for global transaction services in Hong Kong. 'And that translates into a direct positive impact on our business.' Average daily main-board turnover in Hong Kong has increased in each of the past three months and nearly doubled from HK$39.89 billion in February to HK$79.41 billion last month, according to stock exchange data. Trading has tailed off slightly this month but has still held above HK$70 billion in all but three sessions so far. A combination of low-interest rates worldwide and early signs of recovery in the mainland economy have lured investors back to markets in Hong Kong and around the region. And that has meant more work for the securities services business. Often referred to as market custodians, securities services providers can perform a range of responsibilities, acting as stewards for investor holdings, as clearing agents for broker-dealers and as an escrow provider for fund issuers. 'We clear [our clients] of those headaches or cumbersome aspects of their business, so they can focus on what they do best,' said Bruno Campenon, the head of BNP Paribas Securities Services Hong Kong. Securities services providers earn fees based on the duties they provide for their clients. 'The service is very important, and the advisory role we can play for our clients is also very important,' said Ms Ling. 'It's a very sticky business, and it would be very cumbersome to change a custodian bank.' Citi's securities and fund services division falls under the umbrella of its GTS business, which accounted for 17 per cent of the firm's revenue in the Asia-Pacific last year, up from 12 per cent the previous year, according to a Citi representative. The business can still be a volatile one, however, depending on market conditions. And Ms Ling said that keeping pace with developments in technology and changes in market regulation were also challenges for the industry.