Main-board listing candidate Comba Telecom Systems Holdings is facing inventory and receivables pile-ups, as well as a lack of distinctive proprietary technology. The listing candidate has warned potential investors that its customers' credit risks had significantly increased and would probably record a further rise as its business expanded. At the end of April, Comba's trade receivables stood at $319.65 million, accounting for 54.1 per cent of the firm's total assets and nearly four times its sales revenue in the first four months of the year. That contrasts with $192.87 million in receivables at the end of last year - 36.4 per cent of its assets at that time. This means Comba added $126.8 million in receivables in the first four months, on turnover of only $80.55 million. 'As the group's business expands, there may be a need to provide additional sales on credit to its customers, leading to increased customers' credit risk,' Comba says in its listing prospectus. 'The group's financial position could be adversely affected should the group experience any difficulty in collecting payment from its customers.' It is also worth noting that Comba has experienced mounting inventories, with inventory turnover days increasing from 161 days last year to 171 days as of April. Comba stocked $163.9 million in inventory in the first four months. Last year, Comba had a substantial increase in both trade receivables and inventories. The company recorded a 72.6 per cent surge in inventories and 46.3 per cent jump in trade receivables, while its turnover rose by 34.3 per cent. Comba provides wireless coverage enhancement products such as antennas and repeaters as well as system integration services to mobile carriers to eliminate blind spots in their networks. The company aimed at raising between $310 million and $425 million by selling 200 million new shares. The initial public offering (IPO) closes tomorrow. Analysts also highlighted the company's lack of intellectual property rights protection and competition risks. 'Although the group has successfully developed wireless coverage equipment and met the demands of many customers, there does not appear to be much in the way of distinctive technology under patent protection. This is evidenced by the fact that Comba was not actually paid or received actual royalties to/from third parties,' ING Bank said. ING is one of the three co-lead managers of Comba's IPO. HSBC is the sponsor and bookrunner.