Loan repayment stress among middle market and small business borrowers may be worsening, suggests parallel data on unpaid trade debts.Debtor payments under credit insurance claims escalated over the second quarter of 2016, the NCI Trade Credit Risk Index shows.The NCI Trade Credit Risk Index is a periodic index produced by Adelaide-based insurance brokers NCI. The firm specialises in handling credit insurance and derives the index from its claims database.Over the June 2016 quarter, "claims activity was up 62 per cent" over the first half of 2015.Claims are now past their post GFC peak, NCI managing director Kirk Cheesman wrote in a report.