Key summary
Compare equal cash budgets with explicit price assumptions, then identify what a real backtest and a personal savings plan would require.
Dollar-cost averaging and a lump-sum purchase describe when available cash is invested. Neither approach makes a concentrated Samsung or SK hynix position safe. This guide uses transparent arithmetic, not an undocumented historical backtest.
Compare an equal cash budget
For a fair timing comparison, specify the same total starting cash, the purchase dates and what happens to uninvested cash. Someone investing new salary each month is not in the same starting position as someone who already has the full amount available.
A two-purchase illustration
Assume 1,200 currency units are available, share prices are 100 for the first purchase and 50 for the second, fractional shares are allowed, and fees, dividends, taxes and interest on cash are all zero. This invented path illustrates sensitivity, not a prediction.
| Method | Shares after both dates | Value at the assumed final price of 50 |
|---|---|---|
| All 1,200 invested at 100 | 12 | 600 |
| 600 at 100, then 600 at 50 | 6 + 12 = 18 | 900 |
If the second price were 200 instead, the lump sum would buy 12 shares worth 2,400, while the split purchases would buy 6 + 3 shares worth 1,800. Changing the price path changes the comparison. Both examples omit real-world costs and do not identify a superior method for the future.
What a real backtest would need
- Specific securities, price source and start/end dates.
- Adjusted prices or a stated treatment of dividends, splits and other corporate actions.
- Equal cash budgets, contribution timing and uninvested-cash treatment.
- Fees, taxes, currency and assumptions about fractional shares.
- A consistent return measure and several starting dates, including unfavorable periods.
No measured 2015–2025 performance result is provided here. General labels such as "solid in most periods" cannot substitute for that evidence.
Use salary as a cash-flow input, not a portfolio rule
Two people earning the same salary can have different debt, essential spending and near-term needs. Avoid selecting an employer-stock allocation solely from a salary band or an unconfirmed cycle peak. The savings-goal tool can test contributions under your own assumptions without forecasting a stock's return.
Related methods and tax context
- Monthly savings-goal arithmetic
- A constant-return contribution scenario
- NTS share-sale scope, 3 February 2026 (Korean) — relevant tax context, not evidence for the hypothetical investment returns above.
Scope: This is an explanation and planning checklist, not a recommendation to buy, sell or allocate a specified share of your assets. Examples exclude costs and taxes unless stated. Market outcomes and individual employment terms can differ.
Sources and method
Use the dated sources and assumptions stated in this guide. An illustration is not an employer promise, tax assessment or investment forecast. Personal eligibility and the applicable income year need separate checks.
Methods, official resources and help →Use this guide
Build a contribution scenario from your goal and time horizon; the assumed return is not a market forecast.
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