You are an auditor on the Curasafe (CS) Limited engagement for the financial year ending 30 June 2017. CS is a large Australian private health insurer that also provides a range of complementary health management services and life, travel and pet insurance products. During the year, CS transitioned from a government business enterprise to a listed company by way of an initial public offering and listed on the ASX in November 2016. You are currently planning the CS audit and have noted the following information: 

CS maintains an investment portfolio (consisting of mortgage asset-backed securities, hybrid investments and direct property) to meet insurance claims. During the year, it has recorded significant investment income from its portfolio of investment assets in the face of substantial economic and market volatility (interest rates, exchange rate and equity market volatility). 

(a) Identify any key account and related assertions at risk. Briefly justify your answer

(b) Perform one substantive test of detail for each of the identified assertions at risk.