匯率風險下壽險業經濟資本之探討 — 以利率變動型年金商品為例

Abstract

保險法第146條之4規範國外投資總額最高不得超過各該保險業資金45%，而2014年修正增列保險業依保險法規定投資於國內證券市場上市或上櫃買賣之外幣計價股權或債券憑證之投資金額，可不計入其國外投資限額。且因我國市場長期處於低利環境，壽險業即大量以台幣作為融資貨幣買入國外高利率環境下之標的貨幣進行利差交易，本研究擬以經濟資產模型進行資產與負債之模擬，衡量壽險公司的經濟資本與清償風險。\n依據現行壽險公司資金運用決定投資之標的，並以Cox-Ingersoll-Ross (1985)模型模擬國內外短期利率，在無拋補利率平價說下建立匯率模型，以Heston (1993)隨機過程描述資產的變化，並考量壽險公司投資策略決定投資比率，再加入資產之相關性進行模擬；以與壽險公司投資連結之利率變動型年金為商品，加入各項風險因子進行負債價值模擬，諸如死亡率、解約率等因子；資產與負債皆在風險中立測度下以蒙地卡羅法進行模擬10,000次，探討公允價值下壽險公司之清償能力。\n而現行清償能力指標為資本適足比率，但此標準下尚無法完整考慮各風險之相關性，本研究除考量資本適足比率中風險資本總額，亦加入經濟資本進行分析，可得以下結果：\nI.現行RBC風險資本總額介於VaR 99.5%與95%所計算之經濟資本間。\nII.當匯率波動度與國外投資比例增加時，經濟資本亦將顯著增加。\nIII.隨國外債券投資比例增加，風險資本總額增加之幅度亦會加速成長。\nIV.利率變動型年金商品宣告利率之擬定將顯著影響公司面臨之違約風險。

The amendment of Article 146-4 of Insurance Act extended the overseas investment ceiling in 2014 that the International Bond was not included to be counted in overseas investment. Since we have been suffering from the low interest rate for a long time, life insurance industry often uses carry trade to enlarge their earnings.\nIn this paper, the investment targets are chosen on the basis of the current life insurance industry. We simulate the short-term interest rate based on Cox-Ingersoll-Ross (1985) model, establish the exchange rate model by Uncovered Interest Rate Parity, and use Heston (1993) model to simulate stochastic process of assets. Then we consider the life insurance industry’s investment strategy to determine the investment ratio and also import the asset correlation into our models. The interest sensitive annuity policies we used to evaluate the liabilities are linked with life insurance companies’ investment. Some risk factors are also been considered, such as mortality, surrender rate and other factors. Through Monte Carlo simulations by 10,000 times, we analysis the life insurance companies’ solvency under risk neutral measurement by using Risk-Based Capital and Economic Capital. The results show that：\nI.Risk-Based Capital is between Economic Capital calculated by VaR 99.5% and 95%.\nII.When the volatility of exchange rate and overseas investment ratio increase, the Economic Capital will also increase significantly.\nIII.With the increase in the proportion of foreign bond investment, the increase in the Risk-Based Capital will accelerate the growth.\nIV.The declaring interest rate of interest sensitive annuity policy will significantly affect the default risk faced by the life insurance company.