Portfolio risk management is not about predicting which way the market moves. It is about building three tools before volatility hits: a clear time horizon, a set of plausible scenarios, and a pre-written rebalancing rule. This lesson walks through all three with a numeric example. Note: Sahmino does not give buy or sell advice; this is an educational, descriptive framework.
Definitions
Time horizon is the distance to the moment an investor actually needs the money, not the moment they feel the market "should" correct. Risk capacity is how much loss can be absorbed without endangering financial goals; this differs from risk tolerance, the subjective comfort with volatility. An investor can feel psychologically risk tolerant while having low actual capacity, for instance because they need the money within a year. Scenario planning means writing down, before the fact, several plausible paths for key variables (the exchange rate, interest rates, inflation, geopolitical risk) and seeing what the portfolio does under each; unlike a forecast, a scenario does not claim to know the future, it only prepares for several possible ones. Rebalancing means restoring asset weights to their original target once price moves have thrown those weights off. The foundational relationship between risk and return, and which risks actually threaten household savings, is covered in Risk and Return: How Are They Related, a conceptual prerequisite for this lesson.
The process: three steps, in this order
Step one, write down the horizon, do not guess it. A time horizon has three practical bands: short term (under 18 months, mostly liquidity and optionality), medium term (18 months to 5 years), and long term (over 5 years). The shorter the horizon, the lower the capacity to tolerate a price drawdown, because there is not enough time left to recover.
Step two, stress-test the portfolio across several scenarios. A complete scenario has three parts: an assumption about a key variable, an estimated effect on each part of the portfolio, and an action already written down for that path. Three scenarios are usually enough: base (current trend continues), negative (an adverse shock), and positive (favorable acceleration). The key point here is that the negative scenario has to actually be bad, not a mild pullback; a scenario that always ends in the investor's favor is not a scenario, it is wishful thinking.
Step three, decide the rebalancing rule in advance, not in the moment. Two common rebalancing rules are calendar based (for example, every six months) and deviation-band based (triggered once an asset's weight drifts beyond a set distance from target); the details of these two rules, and their trade-off against transaction costs and taxes, with a worked example, are covered in Asset Allocation in Iran's Inflationary Economy. What this lesson adds is this: the output of step two's scenario planning should be the same rule that gets executed at rebalancing time, not a fresh decision made under the pressure of a volatile week.
Worked example
To see how much real volatility can shift a single position's weight, look at an actual, dated example from the Tehran Stock Exchange rather than a purely hypothetical number. The Tehran-listed share "Foolad" (Mobarakeh Steel) traded between a 52-week low of 1,566 rials and a high of 3,371 rials in the year ending August 22, 2026 (31 Mordad 1405), a peak-to-trough spread of about 115 percent of the low. Its last recorded price on that date was 2,533 rials, and its 30-day volatility, as of August 23, 2026 (1 Shahrivar 1405), was reported at 34.1 percent (source: Sahmino market data, drawn from the Tehran Stock Exchange board).
Suppose an investor started with a strategic target of a 10 percent weight in Foolad. If the share price moved from the 2,533-rial level of August 22 toward the 52-week high of 3,371 rials, a gain of roughly 33 percent, while the rest of the portfolio stayed flat, Foolad's actual weight would drift to about 13 percent with no new purchase at all; that is exactly the kind of drift the step-three rebalancing rule needs to have an answer for in advance, not a reaction to a buy or sell queue in the moment. The same logic shows up market-wide: Tehran's benchmark TEDPIX index rose from 5,154,059 points on August 2, 2026 (11 Mordad 1405) to 6,069,888 points on August 23, 2026 (1 Shahrivar 1405), a gain of nearly 18 percent in about three weeks (source: Sahmino market data). A portfolio that held part of its assets in cash or fixed income over that same window saw its equity share rise with no active decision at all; that is precisely what a "positive acceleration" scenario needs to have a ready response for before it happens.
Transmission channel: what this means inside Iran's markets
Scenario planning and rebalancing on the Tehran Stock Exchange run into two structural limits that do not exist in markets with uniform liquidity. First, daily price bands mean that exiting a position quickly under a severe negative scenario can take several trading sessions, not minutes. Second, a buy or sell queue can form at exactly the moment a bad scenario materializes and liquidity matters most. The practical takeaway for scenario planning in Iran is this: a negative scenario should assume from the start that selling a position in full, immediately, at the last quoted price, is not possible, and the portfolio's liquidity bucket should be designed so it does not depend on quickly selling volatile assets. How each asset class functions and how to bucket for liquidity, purchasing-power preservation, and growth is covered in more detail in the asset allocation article above; the logic of spreading capital across low-correlation assets is explained in What Is Diversification?
Common mistakes
- Confusing time horizon with market mood. Horizon means when "you" need the money, not when the market "should" correct.
- Writing only one scenario, usually an optimistic one. A scenario that always ends well is not a decision tool.
- Emotional rebalancing instead of rule-based rebalancing. Selling after one sharp down day is usually the execution of fear, not the execution of a rule written in advance.
- Ignoring liquidity cost in the bad scenario. Assuming any asset can be sold at the last quoted price under any conditions.
Takeaway
Portfolio risk management is not forecasting which way the market goes; it is being ready for several possible paths. Time horizon sets how much loss can be absorbed, scenario planning shows what the portfolio does on each path, and rebalancing executes that pre-written answer without emotion getting a vote. To see how this same logic plays out across markets that react with a lag to one another, the dollar, gold, the bourse, and housing, see Sahmino's previous lesson: What Is Intermarket Analysis? For the full lesson catalog, visit the Sahmino Academy hub.
This piece is purely educational and descriptive and is not a recommendation to buy or sell any asset.
