INTERNATIONAL JOURNAL OF APPLIED SCIENCES AND MATHEMATICAL THEORY (IJASMT )
E- ISSN 2489-009X
P- ISSN 2695-1908
VOL. 10 NO. 4 2024
DOI: 10.56201/ijasmt.v10.no4.2024.pg8.20
K. N. C. Njoku
An optimal Pension investment strategy, under the Constant Elasticity of Variance (CEV) model is developed. The Pension Fund Investor (PFI) invested in both a risky asset (stock) and a riskless asset (Cash account), modeled with CEV process and constant interest rate, respectively. Here, the Pension Fund Administrator (PFA) considered and investigated the relevance/significance of extra stochastic contribution, during non-turbulent period, as a form of extra voluntary contribution, as provided by the Pension Reform Act of 2006, as amended. A constrained Pension Wealth optimization program was developed and transformed into a nonlinear partial differential equation, using the associated Hamilton Jacobi Bellman equation. The explicit solution of the constant relative risk aversion (CRRA) is obtained, using Legendre transform, dual theory, and change of variable methods. I presented and proved theorem on pension wealth investment strategy and the optimal utility function is also presented. It is established herein, with the optimal utility function that the extra stochastic contribution is minimally significant to the satisfaction of the PFI, due to its partial presence in the optimal utility function strategy.
Strategized; Portfolio; CRRA; CEV; Accumulating Pension.
[1] Njoku, K. N. C. (2023). Maximizing an investment portfolio for a DC pension with return
clause and proportional administrative Charges under Weibull force function.
Communications in Physical Sciences, 10(1).
[2] Li, D., Rong, X. and Zhao, H. (2013). Optimal investment problem with taxes, dividends and
transaction costs under the constant elasticity of variance model, Transaction on Mathematics:
12, 243–255.
[3] K. N. C. Njoku, Bright O. Osu, Edikan E. Akpanibah and Rosemary. N. Ujumadu (2017).
Effect of extra contribution on stochastic optimal investment strategies for DC pension with
stochastic salary under the interest rate mode, Journal of Mathematics Finance: 7, 821-833.
[4] Bright O. Osu, Edikan E. Akpanibah and Njoku K. N. C. (2017). On the effect of stochastic
extra contribution on Optimal investment strategies with stochastic salaries under the affine
interest rate model in a DC pension fund. General Letters in Mathematics, Vol. 2, No. 1, Pp.
138-149.
[5] Edikan E. Akpanibah, Bright O. Osu, Njoku K. N. C. and Eyo O. Akak (2017). Optimization
of wealth investment strategies for a DC pension fund with stochastic salary and extra
contributions. International Journal of Partial Differential Equations and Applications, Vol. 5,
No. 1, Pp. 33-41.
[6] Gao J. (2009). Optimal portfolios for DC pension plan under a CEV model. Insurance
Mathematics and economics: 44(3), 479-490.
[7] Witbooi, P. J., Van Schalkwyk, G. J. and Miller, G. E. (2011). An optimal investment strategy
in bank management. Mathematics Methods in the Applied Sciences: 34(13), 1606-1617.
[8] Njoku K. N. C. and B. O. Osu (2019). On the modified optimal investment strategy for annuity
contracts under the constant elasticity of variance (CEV) model. Earthline Journal of
Mathematical Sciences: Vol. 1, No. 169:90.
[9] Njoku K. N. C. and B. O. Osu (2019). Effect of inflation on stochastic optimal investment
strategies for DC pension under the affine interest rate model. Fundamental Journal of
Mathematics and Application, Vol. 8, No. 91-100.
[10] Njoku K. N. C. and Akpanibah E. E. (2022). Modeling and optimization of in a DC scheme
with return of contributions and tax using Weibull force function. Asia Journal of Probability
and Statistics: Vol. 3, No. 16, 1-12.
[11] Udeme O. Ini, Ndipmong A. Udoh, K. N. C. Njoku and Edikan E. Akpanibah (2021).
Modeling of an insurer’s Portfolio and reinsurance strategy under the CEV model and CRRA
utility. Nigerian Journal of Mathematics and Applications. Vol. 31, No. 38-56.
[12] B. O. Osu, K. N. C. Njoku and B. I. Oruh (2020). On the investment strategies, effect of
inflation and impact of heading on pension wealth, during accumulation and distribution
phases. Journal of Nigerian Society of Physical Sciences: Vol. 2, No 170-179.
[13] Delong, L., Gerrard, R., Haberman, S.(2008). Mean-variance optimization problems for an
accumulation phase in a de_ned bene_t plan. Insurance: Mathematics and Economics.
Illustration with a pension accumulation scheme. Journal of Banking and Finance. Vol. 60, No.
127-137.
[14] Othusitse Basimanebotihe and Xiaping Xue (2015). Stochastic optimal investment under
inflammatory market with minimum guarantee for DC pension plans. Journal of Mathematics,
7, 1-15.
[15] Zhang C. and Rong X.(2013). Optimal investment strategies for DC pension with stochastic
salary under affine interest rate model. Publishing corporation. http://dx.doi.org/10.1155/2013/297875
[16] Osu, B. O., K. N. C. Njoku and O. S, Basimanebottihe, (2019). Fund management strategies
for a defined contribution (DC) pension scheme under the default fund phase IV, Commun.
Math. Finance. Vol. 8, No. 169-185.
[17] Akpanibah E. E. and Osu B. O.(2018). Optimal portfolio selection for a defined contribution
pension fund with return clauses of premium with predetermined interest rate under mean
variance utility. Asian Journal of Mathematical Sciences. Vol. 2, No. 2,19-29.