Portfolio revision means changing the mix of securities in a portfolio to keep it in line with the investor’s return goals and risk level. It is needed when the investor’s circumstances or the market change. Strategies are active (frequent, forecast-based) or passive (rule-based). Formula plans such as constant rupee value, constant ratio, variable ratio and rupee cost averaging automate revision. Constraints include transaction costs, taxes, exit loads, regulations and the difficulty of timing.
Say you built a portfolio in January with 60% in equity and 40% in bonds. By December, a strong stock market has pushed equity to 72%. You now carry more risk than you signed up for, even though you never bought a single extra share. Portfolio revision is the process of fixing that: selling some assets, buying others, and bringing the portfolio back in line with your goals.
It is the last stage of portfolio management, after analysis, selection and portfolio evaluation. Below we cover what revision means, why it is needed, the main strategies (including formula plans), and what limits how often you can do it.
Meaning of Portfolio Revision
Portfolio revision means changing the mix of securities in a portfolio, either by changing the proportion held in each asset class or by replacing individual securities. The aim is to keep the portfolio earning the best return for the level of risk the investor accepts. Markets move, companies change and the investor’s own life changes, so a portfolio that was right three years ago is rarely right today.
Read more: Assumptions of modern portfolio theory.
Objectives of Portfolio Revision
- Restore the target allocation after market movements push weights off course.
- Improve returns by replacing securities that no longer meet expectations.
- Control risk so that one stock, sector or asset class does not dominate.
- Match changing goals, such as moving towards debt as retirement or a child’s education approaches.
- Respond to new information, such as a change in a company’s management, a credit downgrade or a change in interest rates.
Need for Portfolio Revision
Two kinds of change trigger revision.
Changes in the Investor
Income rises, a home loan is taken, children are born, retirement comes closer. Each of these changes how much risk the investor can carry and how soon they need the money. A 28-year-old can hold 80% equity; the same person at 58 usually should not.
Changes in the Market and the Securities
Interest rates move, sectors fall out of favour and individual companies stumble. Yes Bank was a large-cap favourite in 2018; by March 2020 it had been placed under an RBI moratorium. Investors who never reviewed their holdings rode it all the way down.
Portfolio Revision Strategies
1. Active Revision Strategy
The investor (or fund manager) changes the portfolio frequently, based on forecasts of where markets, sectors or stocks are heading. It aims to beat the market but involves more research, more trading and higher costs. It suits investors who believe markets are not fully efficient and who have the time and skill to analyse them.
2. Passive Revision Strategy
The investor changes the portfolio only according to predetermined rules, not forecasts. Rebalancing to a fixed allocation once a year, or whenever weights drift by more than five percentage points, is a typical passive approach. Formula plans are the classic example. Costs are lower and decisions are less emotional.
| Point | Active revision | Passive revision |
|---|---|---|
| Basis | Forecasts and analysis | Pre-set rules |
| Frequency | Frequent | Periodic or when limits are breached |
| Cost | Higher (trading, research) | Lower |
| Goal | Beat the market | Keep risk on target |
| Suits | Experienced, hands-on investors | Most individual investors |
Formula Plans
A formula plan is a set of mechanical rules that tell the investor when to shift money between an aggressive portfolio (usually equity) and a conservative portfolio (usually bonds or debt funds). The idea is to force the investor to buy low and sell high without having to predict the market.
Read more: Capital asset pricing model.
Assumptions of Formula Plans
- Share prices move in cycles, rising and falling around a trend.
- The investor can identify a conservative and an aggressive portfolio.
- The investor sticks to the rules even when the market mood says otherwise.
- Shares and bonds are not perfectly correlated, so one can cushion the other.
Types of Formula Plans
Constant rupee value plan. The investor keeps a fixed rupee amount in equity, say ₹5 lakh. If the equity portion rises to ₹6 lakh, ₹1 lakh is sold and moved to bonds. If it falls to ₹4 lakh, ₹1 lakh is moved from bonds into equity. In practice, investors act only when the value moves beyond a set band, such as 10%, to limit trading.
Constant ratio plan. The investor keeps a fixed ratio between equity and bonds, such as 50:50. When equity grows to 58% of the portfolio, the excess is sold and moved to bonds until the ratio is back to 50:50. This is the rebalancing method most financial planners use today.
Variable ratio plan. The equity share changes with market levels. When the market is cheap (for example, when the Nifty’s price-earnings ratio is low by historical standards) the equity share is raised; when it is expensive it is cut. Balanced advantage funds in India follow a version of this.
Rupee cost averaging. The investor puts the same amount into a security at regular intervals regardless of price, so more units are bought when prices are low. A monthly SIP in a mutual fund works exactly this way. AMFI data shows monthly SIP inflows crossed ₹26,000 crore for the first time in December 2024, which tells you how widely Indian investors now use this formula.
Constraints in Portfolio Revision
| Constraint | What it means |
|---|---|
| Transaction costs | Brokerage, exchange charges, STT (0.1% on equity delivery trades) and GST reduce the gain from every switch. |
| Taxes | Selling equity held for under 12 months attracts 20% short-term capital gains tax; longer holdings pay 12.5% on gains above ₹1.25 lakh a year (rates since 23 July 2024). Frequent revision can hand a large part of the return to the taxman. |
| Exit loads | Many mutual funds charge around 1% if units are redeemed within a year. |
| Statutory rules | Mutual funds, insurers and pension funds must follow SEBI, IRDAI or PFRDA limits on what and how much they can hold. |
| Intrinsic difficulty | Knowing when and what to change is hard. Revising too often turns investing into trading; too rarely lets risk drift. |
A Practical Rule of Thumb
For most individual investors, a passive approach works well: decide a target allocation, review it once a year, and rebalance only when an asset class drifts more than five percentage points from target. Use fresh SIP money to rebalance where possible, since buying more of the underweight asset avoids selling and the tax that comes with it.
