A Systematic Investment Plan, or SIP, is a simple way to put money into the market at regular intervals. Instead of investing a large amount at one time, an investor puts in a fixed amount each month. This approach can make market investing easier and can reduce the risk of poor timing.
But there is an important question that often gets missed.
What happens when the SIP goes into a concentrated index?
A concentrated index has a large share of its value in a small number of companies or sectors. An investor may feel that a monthly SIP makes the investment safer because the money enters the market at different prices. That is true to some extent, but it does not remove concentration risk.
The key point is simple: a SIP spreads your investment across time, not across companies.
What Is Concentration Risk?
Concentration risk arises when too much of a portfolio depends on a small group of investments. If those companies or sectors face a major fall, the portfolio can also face a large decline.
Consider an index where the top five companies make up 60% of the total index. This means more than half of the money in that index has exposure to just five companies.
Now consider another part of the same index. Suppose one sector makes up 45% of the index. A major problem in that sector could have a large effect on the index, even if other sectors perform well.
This is what makes concentration different from market volatility.
Market volatility refers to changes in prices over time. Concentration refers to how much of your money depends on a limited set of companies or sectors.
A SIP can address the first issue to some extent. It does not directly address the second.
How Does Rupee-Cost Averaging Work?
A SIP follows the idea of rupee-cost averaging. The investor puts a fixed amount into the market at regular intervals, regardless of whether prices are high or low.
When prices are high, the fixed amount buys fewer units. When prices are low, the same amount buys more units.
For example, suppose an investor puts ₹10,000 into an index every month. When the index level is high, ₹10,000 buys fewer units. If the index falls, ₹10,000 buys more units.
Over time, the investor gets exposure at different market prices instead of relying on one entry point.
This can reduce the effect of a bad entry date. It can also make it easier for an investor to stay with a long-term plan during periods of market stress.
However, this benefit has a clear limit.
Rupee-cost averaging changes when you buy. It does not change what you buy.
Why SIP Does Not Remove Concentration Risk
Suppose a concentrated index has the same structure throughout the year. Its top five companies account for 60% of the index, while one sector represents 45%.
An investor puts ₹10,000 into this index each month for 12 months.
The investor has now spread the purchases across 12 different dates. That can help with timing risk. But the money still follows the same index structure.
If the top five companies remain at a 60% weight, a large part of each monthly investment goes toward those companies.
The same applies to the 45% sector exposure.
So, after a year, the investor has not created meaningful diversification simply because the money entered the market twelve times. The portfolio still has a strong dependence on the same companies and sector.
This distinction is important because timing risk and concentration risk come from different sources.
SIP Can Help With Timing Risk
Imagine an investor has a large amount of money and puts the entire amount into the market just before a sharp correction.
That investor may see a major fall soon after the investment.
A SIP can reduce this particular risk because the investor does not put the entire planned investment into the market on one date. Instead, the money enters at several points.
If prices fall after the first few purchases, later instalments can buy more units at lower prices.
This does not guarantee a profit. Markets can continue to fall, and a concentrated index can face a long period of weakness. Still, a SIP can reduce the dependence on one entry point.
It can also provide a simple investment habit. The investor does not need to decide every month whether the market looks attractive.
What Happens During a Major Sector Fall?
The limits of a SIP become clearer when one sector faces a serious problem.
Suppose the index has a 45% weight in one sector. A major change in regulation, technology, demand, competition, or profits could hurt companies in that sector.
If those companies fall sharply, the index can also suffer a large decline.
A monthly SIP does not prevent this.
In fact, if the investor continues the SIP while the sector remains weak, more units of the same index will be purchased. If the index later recovers, this can work in the investor’s favour. But there is no guarantee of such a recovery.
The real issue is that every new SIP instalment continues to carry the same concentration.
Does a Longer SIP Period Solve the Problem?
A longer investment period can reduce the importance of short-term market movements, but it does not automatically solve concentration.
An investor who stays invested for ten years in a concentrated index still owns a concentrated index.
Time can help when the underlying companies and businesses grow over the long term. But time alone cannot turn a concentrated portfolio into a diversified one.
This is why investors need to separate two questions.
The first question is: Am I comfortable with my entry process?
The second is: Am I comfortable with the assets I own?
A SIP can be useful for the first question. It does not answer the second.
Concentration Is Not Always a Problem
It is also important not to assume that concentration is always negative.
A concentrated index can have strong exposure to companies that perform very well. If those companies deliver strong earnings and business growth, the index can produce strong returns.
The problem is not simply that the index has fewer companies or a high sector weight.
The main issue is the level of risk an investor can accept if those major holdings underperform.
An investor who understands the concentration and has other assets that provide diversification may use such an index as part of a wider portfolio.
An investor whose entire equity portfolio depends on the same small group of companies faces a different situation.
How Can Investors Think About the Risk?
The first step is to look beyond the index name.
Check the weight of the top five and top ten companies. Look at sector weights. Check how much of the portfolio depends on one industry.
Then look at the rest of the portfolio.
If an investor already has other funds or investments with similar companies and sectors, the actual concentration may be higher than the index factsheet suggests.
For example, owning two different funds does not always mean owning two different sets of risks. Both funds may have large exposure to the same companies.
Portfolio diversification depends on the underlying holdings, not just the number of funds.
The Simple Takeaway
A SIP is a method of investing. It is not a method of diversification.
Rupee-cost averaging can help reduce the risk of putting a large amount into the market at an unfortunate time. It can also create a disciplined investment routine.
But it cannot remove the risk that comes from heavy exposure to a small number of companies or a single sector.
If an index has 60% in its top five companies and 45% in one sector, those exposures remain important even when an investor buys through a SIP.
So the easiest way to remember the difference is this:
SIP spreads your purchases across time. Diversification spreads your money across different sources of risk.
Both can have a role in an investment plan, but they solve different problems. An investor who wants to address concentration risk needs to examine the portfolio’s actual company and sector exposure rather than assume that a regular monthly SIP has already created enough diversification.
ALSO READ: Should Exporters Hedge More When the Rupee Is Stable?
