Index investing: 3 things you need to know about an equity index
Endowus Insights

Leap into prosperity this CNY 💰     Get an $88 head start to growing your wealth.

Leap into prosperity this CNY 💰Get a $88 head start to growing your wealth.

Index investing: 3 things you need to know about an equity index

Aug 2023
Apr 2020
investing - stocks - indices

As a long-term index investor, we need to know whether the index fund that we are investing in has a level of risk and exposure that we are comfortable with.

This is especially important now that there are more indices than stocks, and index and exchange-traded fund (ETF) providers have been coming up with new indices for retail investors to invest in, such as the recent Work From Home ETF (ticker symbol WFH).

Back to basics: What is an equity index?

An equity index refers to a collection of stocks or shares that represents a segment of the financial market.

For example, the Singapore Straits Times Index (STI) includes the top 30 companies listed on the Singapore Exchange (SGX). In contrast, the MSCI All Country World Index (ACWI) consists of companies that are listed in developed countries and emerging markets. Meanwhile, the S&P 500 index represents 500 major companies listed in the US.

Let's take a look at some common equity indices and how each index is constructed.

Indices and their construction methodologies:

Index name Index provider(s) Weighting method Common ETF tickers Exposure Market cap
FTSE Straits Times Index SPH, FTSE, SGX Market capitalisation ES3, G3B Geographical: Singapore Large cap
FTSE All World Index FTSE Market capitalisation VWRA Geographical: global Large and mid cap
Technology Select Sector SPDR Index State Street SPDR Market capitalisation XLK Industry sector: technology, telecom Large cap
S&P 500 Equal Weight Index Standard & Poor's Equal weight RSP Geographical: US Large cap

Source: Endowus Research

Not only do the index providers ensure that the listed companies meet the index factors or criteria, they may also choose to include or exclude listed companies based on profitability, listing history, and liquidity of the shares.

Now that we have the basics out of the way, let's look at the three things you need to know about equity indices before you begin index investing:

1. Weighting method of indices

There are two main types of weighting methods: market capitalisation and equal weightage, along with price weightage.

To illustrate this, let's assume we are investing in a so-called "Singapore Bank Index", which is composed of three banks (DBS, OCBC, and UOB).

Understanding weightage through the hypothetical Singapore Bank Index:

Components of the hypothetical index Market cap Market cap weightage Equal weightage
DBS S$84.1b 45.1% 33.3%
OCBC S$55.3b 29.7% 33.3%
UOB S$46.9b 25.2% 33.3%
Total S$186.3b 100% 100%

Note: For illustrative purposes only. The estimated market capitalisations of the Singapore bank equities are based on information on the SGX website as of 22 Aug 2023.

Market capitalisation basically refers to the value of the shares that are available for trade on the stock market exchange. The higher the share price, and the greater the number of shares available for trade, the higher the market capitalisation. As a result, when the share price increases or when new shares are issued, the weightage will change.

However, for an equal-weighted index, the weightage of the stocks will always be the same within the index, regardless of their share price movements

Because of the different weightage, the risk and performance of a market cap-weighted fund and an equal-weighted fund will be different, despite having the same underlying shares.

2. Exposure types of equity indices

The exposure type and geographical exposure of the funds let us know how the equities are classified, and which category of index investment we are investing in.

For example, Apple, an American company listed in the US, is categorised under the "Information Technology" industry sector by index providers. Nestle is a Swiss company listed in Switzerland, and is categorised under "Consumer Staples" by index providers.

Due to the characteristics of Apple and Nestle, it is unlikely that you will see them in the same index other than in broad-based indices like the FTSE All World Index or the MSCI All Country World index.

The more specific the index criteria, the smaller the number of portfolio assets that can be under the index. That also brings us to the next point.

3. Risk of exposure, or lack thereof, in your equity index investment

The most important point for index investors is to understand not just the exposure type and geographical exposure of the index funds, but also the investable universe of financial assets within the exposure.

Any index fund that replicates broad-based indices with wide geographical and sector exposure, such as the FTSE All World Index and MSCI All Country World Index, are suitable for long-term investing through market cycles. The index providers have a huge range of companies to choose from, and will end up with a diversified and robust portfolio. These index providers will also be able to maintain the performance of the portfolio, as existing companies are replaced if they do poorly.

The same cannot be said for indices that have a narrower exposure: the MSCI Japan Index, for example, has done poorly in the past 30 years, as seen from the comparison between MSCI Japan and MSCI All Country World Index Ex Japan (ACWI excluding Japan) below.

Low cumulative returns of MSCI Japan relative to MSCI ACWI Ex Japan:

chart of cumulative returns of MSCI Japan relative to MSCI ACWI Ex Japan
Source: MSCI Research

For Singapore index investors, the STI seems like an intuitive choice to invest in. It is denominated in Singapore dollars, has many companies Singaporeans are familiar with, and has low-cost Regular Savings Plans for STI ETFs, making it accessible to all.

However, local index investors have to take note of the narrow exposure of the STI — it is made up of only 30 SGX-listed companies, with a huge concentration in the financial services and real estate sectors, along with a lack of exposure in technology companies.

Also, as the index mandate is to invest only in SGX-listed companies, it has to contend with the shrinking number of SGX-listed companies, as large Singapore brands such as Razer, Osim, and Sea choose to list overseas.

With a clearer understanding of how indices work and which indices are more suitable for long-term investments, the next step will be to understand how to choose the appropriate funds for the index exposure that you are investing in.

Get started with Endowus

At Endowus, we work with fund management companies to screen and bring in low-cost, best-in-class unit trusts that are suitable for Singapore investors and available for investments with Cash, SRS, and CPF. We also rebate any trailer fees to lower costs for clients.

The process of screening and down-selecting appropriate funds allows our clients to be exposed to the markets in the most cost-efficient manner, even relative to ETFs. This effectively translates to higher returns over the long term.

If you're interested in investing in an index fund, explore the list of curated investment funds on the Endowus Fund Smart platform. With Fund Smart, investors can buy a single fund or customise their ideal portfolio with multiple funds in just a few minutes. For those keen on getting exposure to top US stocks, learn more about how to select an S&P 500 index fund in this article.

Prefer to leave the fund selection to the experts? The Endowus Flagship Portfolios are made up of best-in-class funds, designed to give investors broad exposure to tens of thousands of companies with different market capitalisations that are listed on various global markets, providing the benefit of geographical and sectoral diversification. The Flagship Portfolios can also be tailored to include exposure to bonds, so you can diversify your asset allocation beyond stocks.

Some of the index funds that are part of the Flagship Portfolios (as of August 2023) include the BlackRock iShares US Index Fund, which tracks the S&P 500 index; the BlackRock iShares Developed World Index Fund, which tracks the MSCI World Index; and the Amundi Index MSCI Emerging Markets Fund, which tracks the MSCI Emerging Markets Index.

To get started with Endowus, click here.

Next on the Endowus Fin.Lit Academy

Read the next article in the curriculum: What are bonds, and why should you invest in them?


Investment involves risk. The value of investments and the income from them can go down as well as up, and you may not get the full amount you invested. Past performance is not an indicator nor a guarantee of future performance. Rates of exchange may cause the value of investments to go up or down. Individual stock performance does not represent the return of a fund. 

Any forward-looking statements, prediction, projection or forecast on the economy, stock market, bond market or economic trends of the markets contained in this material are subject to market influences and contingent upon matters outside the control of Pte. Ltd (“Endowus”) and therefore may not be realised in the future. Further, any opinion or estimate is made on a general basis and subject to change without notice. In presenting the information above, none of Endowus Pte. Ltd., its affiliates, directors, employees, representatives or agents have given any consideration to, nor have made any investigation of the objective, financial situation or particular need of any user, reader, any specific person or group of persons. Therefore, no representation is made as to the completeness and adequacy of the information to make an informed decision. You should carefully consider (i) whether any investment views and products/ services are appropriate in view of your investment experience, objectives, financial resources and relevant circumstances. You may also wish to seek financial advice through a financial advisor or the Endowus platform and independent legal, accounting, regulatory or tax advice, as appropriate.

More on this Tag
investing - stocks - indices

Table of Contents