本文利用隨機控制理論，延續Chang et al. ( 2002 )，採用總和精算成本法，考慮提撥率風險( Haberman and Sung ( 1994 ) )極小的情況下，推導確定給付退休基金之最適提撥與資產配置策略封閉解，資產配置部分考慮股票市場投資組合、永續債券、現金三種部位。
套用公務人員退撫基金第四次精算報告之數據，透過Matlab重覆模擬1,000次，數值結果如下：
1.正常成本與提撥金額呈遞增趨勢，且兩數據差距甚小，符合風險評估函數所設定之提撥率風險極小化的要求。十年控制期間中，正常成本成長5.32倍，從1.03億增加至5.49億；提撥金額成長16.65倍，從0.33億增加至5.56億。275期以前正常成本大於提撥；275之後提撥大於正常成本。
2.初期提撥金額小於給付金額，且投資報酬不足以彌補其差額，因此造成基金規模縮小，但由於提撥金額成長速率大於給付支出，使得基金規模下降程度趨緩，隨後開始穩定成長。十年控制期間中，基金規模從起始的1,000億下降至840億，再上升至約1,314億。
3.股票與債券之持有或放空的部位越多，基金報酬率波動越大，基金規模越大時，可承擔風險的容量增加，因此傾向高風險投資；基金規模越小時，風險承受度變小，所以投資策略反而趨向保守。股票最多持有99.18%、放空90%；債券最多持有293.5%、放空140.14%。 / In this study, we continue using the model of Chang et al. ( 2002 ), which is based on stochastic control theory to study the dynamic funding policy and investment strategy for defined benefit pension plans. The model includes three investable assets: stock market portfolio, consol bond, and cash. We apply “Aggregate Actuarial Cost Method,” so only the contribution rate risk proposed in Haberman and Sung ( 1994 ) is considered when measuring the performance.
In addition, we analyzed the data from Taiwan Public Employees Retirement System (Tai-PERS) investigate the optimal contribution and asset allocation through the proposed model and arrived at the following conclusion:
1.The trend of increasing normal cost and contribution as well as the small disparity tally with the requirement of minimum contribution risk as defined in the loss function.
2.In the beginning, the return of investment and contribution are insufficient to cover the benefit payment, causing the fund level to shrink; but as the rate of contribution increases over time and surpasses the benefit payments, the fund level will cease to shrink, and start to grow gradually.
3.There is a positive correlation between the fund level and the risk of investment. In other words, the larger the size of the fund level, the higher the possibility of holding or short selling risky assets.
| Identifer | oai:union.ndltd.org:CHENGCHI/G0097358021 |
| Creators | 葉倩妏, Yeh,chien wen |
| Publisher | 國立政治大學 |
| Source Sets | National Chengchi University Libraries |
| Language | 中文 |
| Detected Language | English |
| Type | text |
| Rights | Copyright © nccu library on behalf of the copyright holders |
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