Part Two

At 35 years, all equities will be purged from the portfolio to maximize safety (10% corporates, 70% Treasuries, 20% cash). This means that the fund will generate an average return of (0.48+2.31+.1) = 2.89%

Using Excel, it is determined that the value of the portfolio when John and Mary retire and Paul enters assisted living needs to be $5,775,134. With that level, the portfolio will have money until Paul turns 85, at which point the portfolio will no longer have value. The assumption here is that the payments for the assisted living around going to be held in cash, so there is a need for 20% of the portfolio to be cash, and much of the rest is Treasuries so that it is liquid. Maturities will need to be staggered so that there is a current portion reaching maturity each year, to avoid having to sell below par, thereby removing on key risk factor at the stage when the portfolio has the highest degree of risk aversion. For this reason as well, bond funds cannot be substituted for bonds, because they fluctuate in value with the prevailing interest rates.

Working backwards from the $5,775,134 figure, we need to determine how much John and Mary need to invest in this account. The return during the first 25 years will be (.75*10.3 + .15*4.8 + .1*3.3) = 7.725 + .72 + .33 = 8.775%. The returns from years 26-35 will be (.3*10.3+.4*.48+.3*3.3) = 3.09+1.92+.99 = 6% .

The annual contributions need to be $36,972. This equates to $3,081 per month. Note that compounding is not assumed to be monthly in this example. There are three reasons for that. The first is that fixed income does not pay monthly. The second is that equities do not follow a linear compounding pattern either. The third...

Assuming compounding would lower the monthly contribution required, and could lead to shortages in the last few years of the portfolio if the assumptions about the returns do not hold.
With respect to specific asset allocation, it is important to keep in mind that the longer the time frame, the riskier the portfolio will be, in order to build up the equity. Within the asset classes, there will also need to be more risk in the earlier years. So in the first few years, equities can have a higher percentage of small cap and some international. As the portfolio moves closer to year 35, the equities should be more secure. This will affect the earnings of the portfolio, but since the timing of market moves is not known, an average rate has been used.

It is also important that post-35 years, there needs to be cash in the portfolio to allow for the portfolio to meet Paul's needs. At that point, his parents can remain trustees, but as they age they will need to think about having a trustee who can manage this money, as the elderly Paul will not be able to do so. This is especially important during these latter years of Paul's life, because at that point, if the money runs out, the result could be catastrophic. Lastly, the parents need to revisit the portfolio occasionally. They need to make annual investments -- holding monthly deposits in Treasuries until the right opportunity presents itself is a good idea -- but the annual examination of the account is an important element of control. The portfolio should be diversified and therefore should behave roughly in line with the market, and it is important that not only does this occur but that there are not too…