Suppose your $2,000 portfolio holds $1,800 in broad stock index funds, plus $120 in Harbor Coffee and $80 in Tessel Software, two fictional companies. You call the funds your “core.” That sounds steady, but every dollar is still in stocks.
You have $200 a month to add and want a mix of stocks, bonds and cash. You do not need another stock idea. You need a place for the shares you already own, a limit on their size and a way to reach your chosen mix.
Give each holding two labels
An indexed core is the main part of your portfolio, built around broad index funds. A satellite allocation is the smaller part reserved for choices such as individual stocks or a narrowly focused fund. Here, that part is your active sleeve.
Even an index fund can be a satellite: adding a narrow industry fund is an active choice about where to concentrate.
Core and satellite describe roles; stocks, bonds and cash describe asset classes. Your core can combine stock and bond index funds with cash set aside by the plan. A core made entirely of stocks still carries stock-market risk. Calling something “core” does not make it safe.
The structure gives existing stock picks a defined place and a limit. A portfolio of diversified funds with no active sleeve can be a complete plan. A satellite is optional equipment.
Locate the stocks you already own
Your starting portfolio is 90% core and 10% active. It is also 100% stocks. Both descriptions are true.
For this exercise, suppose you have already chosen 60% stocks, 30% bonds and 10% cash, with an active cap of 10% of the whole portfolio. The $200 of direct stocks belongs inside the 60% stock allocation. Adding it on top would change the plan.
Harbor is $120 ÷ $2,000 = 6% of the portfolio; Tessel is 4%. Inside the $200 active sleeve, they are 60% and 40%. A small sleeve can still be dominated by one company.
Those percentages count only the shares you hold directly. Any Harbor shares inside a fund add to your exposure to the same business. The funds' holdings reveal that overlap.
Before adding more, compare the purchase with both your single-position limits and your cap for all active holdings together. A 10% cap leaves room to hold less, including zero.
Choose how to reach the mix
To isolate the effect of moving money, keep prices flat and leave out income, taxes and costs for both routes.
Change it with contributions
One route puts each $200 monthly contribution into $150 of broad bond index funds and $50 of cash. After six months, that adds $900 of bonds and $300 of cash beside the unchanged $2,000 of stocks. The total is $3,200; stocks still make up 62.5%.
Month seven's $200 can go into $40 of indexed stocks, $120 of bonds and $40 of cash. You reach $3,400: $2,040 stocks, $1,020 bonds and $340 cash. Divide each by $3,400 and you get 60/30/10.
The direct stocks remain worth $200, now about 5.9% of the portfolio. You have made them smaller in proportion without selling them.
Change it with a sale
Back at the original $2,000 balance, a sale can reach the target without waiting for savings. Selling $800 of indexed stocks releases $600 for bond index funds and $200 for cash. That leaves $1,000 indexed stocks, $200 direct stocks, $600 bonds and $200 cash: the same 60/30/10 split.
In each bar, indexed and direct stocks together make up the stock allocation. The dark segment stays worth $200, even as contributions shrink its share.
| Route | New money | Trade-off |
|---|---|---|
| New cash | $1,400 over 7 months | More time above stock target |
| Sale | $0 | Tax and costs to check |
The trade-off is time spent with more stock exposure than you want. Price moves or a missed deposit change the seven-month result. New money helps only if it arrives soon enough for the risk you can carry.
For either route, check which funds your account offers, purchase minimums and trading costs, including fees or spreads. A sale also needs a tax check for the shares being sold.
The reason for selling here is to reach the chosen asset mix. Your existing rebalancing rule governs later adjustments.
Keep score for the active sleeve
A positive account return can hide an expensive stock-picking decision.
For a separate one-year comparison, use the $2,000 portfolio just after the sale: $1,800 core across indexed stocks, bonds and cash, plus $200 active.
Suppose the core returns 6%, the sleeve loses 20% and a matching passive stock fund earns 10%. Returns include reinvested income and investment costs, before personal taxes or inflation. No money enters, leaves or moves between the parts during the year.
The core gains $108 and the sleeve loses $40. Together they finish at $1,908 + $160 = $2,068, a 3.4% gain.
The passive fund is your sleeve benchmark: the investment serving the same job as the selected stocks, chosen before the period starts. Comparing the stock picks with a core that also holds bonds and cash mixes up different jobs.
Replace only the sleeve with that fund. The core still ends at $1,908, while the $200 grows to $220. Total: $2,128, a 6.4% gain. This is the all-passive counterfactual: what the portfolio would have earned with passive holdings in place of your active picks.
The active choice left you $60 behind, costing 3 percentage points of portfolio return. With no money moving between the parts, its impact is:
10% × (−20% − 10%) = −3 percentage points. The account made money while the active choice held it back.
Move money from the core into the sleeve and it counts as a deposit when measuring the sleeve alone. The whole account receives no new money. Measuring returns explains how to separate deposits from gains.
A decision that fits this example could be: “Use contributions while I can carry the extra stock exposure. Add nothing to the active sleeve. Review the mix after the next $200 deposit, or sooner if I cannot afford it.” If waiting leaves too much risk, the sale route deserves an earlier look.
Alongside the 10% active cap, that gives your investment policy statement a route and a next review. The portfolio has a structure without needing a new stock idea.
In short
- Core and satellite describe roles inside the same asset allocation.
- A portfolio can be 90% indexed core and still be 100% stocks.
- Contributions change the mix gradually; sales change it sooner with costs to check.
- An active sleeve is optional; its cap limits its size, and a matching passive alternative tests its results.