The full guide
Rebalancing a Sri Lankan portfolio — keeping your risk on target without paying away your returns
Reviewed and updated July 16, 2026 · Written for Sri Lankan investors and borrowers
A portfolio you set up as 70% equities and 30% fixed income will not stay that way. A strong year on the CSE might leave you at 80/20 — holding more risk than you chose — while an equity slump leaves you underweight just when shares are cheap. Rebalancing is the discipline of periodically restoring your policy weights, and it is one of the few mechanical habits that forces you to sell high and buy low.
For Sri Lankan investors the wrinkle is transaction costs: a round trip on the CSE costs about 2.27% for individuals, so how you rebalance matters as much as whether you do.
Policy weights and drift
Your policy weights are the target allocation you chose deliberately — say 70% equities, 30% government securities and deposits — based on your horizon and risk tolerance. Drift is the gap between current and target weights caused by markets moving. Drift is not automatically bad; it is simply your portfolio taking on a risk profile you never chose. A Rs. 10 million portfolio that drifts from 70/30 to 80/20 now holds Rs. 1 million more equity risk than intended.
When to rebalance: calendar versus threshold
Two workable rules exist. Calendar rebalancing checks and resets the portfolio on a fixed schedule, typically annually. Threshold rebalancing acts only when an asset class drifts beyond a band, commonly 5 percentage points from target. Threshold rules respond faster to big moves; calendar rules are simpler and prevent over-trading. A hybrid — check quarterly, act only outside the 5-point band — suits most people.
What does not work is rebalancing by feel. The whole value of the exercise is that it removes emotion: it makes you trim equities after euphoric rallies and add to them after painful falls, exactly when instinct says to do the opposite.
The CSE cost problem — and the contribution solution
Selling Rs. 1 million of shares to fix the 80/20 drift above costs about Rs. 11,200 in transaction costs on the sale alone; a full round trip in and out of the market runs to roughly 2.27%, or about Rs. 22,700 per million traded. Rebalance by selling every quarter and the costs quietly become a persistent drag on returns.
The cheaper method is cash-flow rebalancing: direct new monthly contributions, dividends, and maturing FD proceeds entirely into whichever asset class is underweight. A Rs. 10 million portfolio receiving Rs. 100,000 a month in fresh savings can correct a 5-point drift within several months without selling anything. Reserve actual selling for large drifts that contributions cannot fix within a reasonable time.
A worked example
Target: 70% equities, 30% fixed income on a Rs. 10 million portfolio, so Rs. 7 million and Rs. 3 million. After a rally, equities are worth Rs. 8 million and fixed income Rs. 3 million — a Rs. 11 million portfolio now split roughly 73/27. New targets are Rs. 7.7 million and Rs. 3.3 million. Within the 5-point band, you could simply direct all new savings to fixed income. If equities had instead reached Rs. 9.5 million (76/24, still within band but drifting), the same rule applies with more urgency; beyond the band, sell Rs. 0.75 million of equities, accepting roughly Rs. 8,400 in sale costs as the price of restoring your chosen risk.
Rules that keep you disciplined
Write the policy down before markets test it.
Define which balance sheet the targets cover before calculating a trade. EPF, Treasury bills, FDs, unit trusts, and CSE shares may all belong to the retirement portfolio even though they sit in different statements; counting only the CDS account can make a household that is already heavy in fixed income buy even more. A home used by the family is usually tracked separately because selling ten percent of it to rebalance is not practical. Keep one worksheet showing each holding, its current value, asset class, target, and permitted band. After every contribution or maturity, update that worksheet and let the calculator produce the smallest set of purchases needed. This creates an audit trail and prevents two family members from unknowingly “correcting” the same shortfall in separate accounts.
- Fix your target weights and a 5-percentage-point rebalancing band in writing.
- Check quarterly; act only when a band is breached.
- Rebalance with new contributions and income first, sales last.
- Never skip a rebalance because you feel confident about the overweight asset — that feeling is the reason the rule exists.
Sources & further reading
This guide is educational and reflects publicly available rules and market conventions at the review date. Tax rates, bank rates, and regulations change — verify current figures with the institution or the Inland Revenue Department before making a financial decision. Nothing here is financial, tax, or investment advice.