Say you open a brokerage account on a Tuesday night, buy one broad S&P 500 fund, then add a slice each of Nvidia and Apple because you know the names. Three holdings, hundreds of companies behind them. Feels diversified, right?
It’s thinner than it looks.
At the end of July 2026, the ten biggest companies in the S&P 500 made up more than 39% of the index’s market value, according to Capital Group’s Anita Patel. That tops even the dot-com peak of March 2000. Capital Group sells actively managed funds, so it has a stake in this argument, but it takes its weights from FactSet, and other analysts put the figure at around 40% too.
Here’s the tension for any Singapore beginner. US stocks are still the easiest deep market to reach from here, and the index most people grab first has turned into a concentrated bet on tech and chip giants at the centre of the AI build-out. Both things are true. This guide covers how to start, what to buy first, and where the catch sits.
Why look at the US at all?
SGX leans toward banks and property, and large-scale technology barely registers on it. The US market fills that gap, and its depth means most shares are easy to buy and sell.
One quirk: you’ll trade at night. US hours run roughly 9:30 pm to 4 am Singapore time in the northern summer, and an hour later in winter. Currency and tax come with the territory too, and the risks section below covers both.
How do you start?
It’s mostly paperwork:
- Pick a broker licensed by the Monetary Authority of Singapore that offers US market access.
- Verify your identity and fund the account. Converting SGD to USD costs something, so check the exchange rate on offer.
- Place a first order. Many platforms sell fractions of a share, so a small budget still gets you in.
- Set a recurring monthly buy into the same holding. It spreads your entry price and spares you from timing an overnight market.
What does the index actually hold?
The S&P 500 still has 500 names. What changed is how unevenly they shape your result.
| Layer | Share of S&P 500 |
| Five largest companies | 30% |
| Ten largest companies | over 39% |
| Semiconductors (one industry) | 17% |
| Information technology (one sector) | 37% |
As at 31 July 2026. Source: Capital Group, FactSet.
Look at the semiconductor row. One industry takes 17% of the index, so a beginner who thinks “I own America” also owns a big helping of chip makers.
Prices lean on expectations too. At the end of 2025, the top ten took about 41% of market value but produced roughly 32% of earnings, per Goldman Sachs’ year-end review as summarised by Hedge Fund Alpha.
When those names stumble, the whole fund feels it. Capital Group found that seven stocks accounted for more than half of the S&P 500’s decline in the 2022 downturn, and again after Liberation Day in 2025. Five hundred companies, seven doing most of the damage.
Now the counterintuitive part: concentration isn’t a one-way street. S&P 500 earnings grew 52% in the second quarter of 2026, with eight of the index’s 11 sectors posting double-digit growth, so leadership may be broadening beyond tech. A fund that tracks the index follows along automatically. Nobody times that.
What should beginners buy first?
Start broad, then narrow. A US index ETF gives you instant diversification by company count, and blue chips or fractional shares come later.
The catch is overlap. Before you add a big-name stock on top of an index fund, read the fund’s top-ten list on its fact sheet. If Nvidia or Apple already sits there, a fresh purchase is a second helping, not a new ingredient. Doubling up on a top-ten name isn’t spreading risk; it’s more eggs in the same basket. Some investors soften the tilt with equal-weighted or global funds, and each choice has its own trade-offs.
What are the risks?
Start with the one most beginners never hear about. US estate tax applies to US assets that non-US residents hold above just US$60,000, at rates from 18% to 40%, according to Singapore guides from Syfe and StashAway. That covers shares of US companies and US-domiciled ETFs, and US$60,000 is a modest portfolio, not a rich person’s problem. Funds domiciled outside the US generally sit outside that net, though a tax adviser should confirm it for your case.
Dividends carry a 30% US withholding tax, since Singapore has no tax treaty with the US. Singapore itself generally doesn’t tax capital gains.
Currency is the quiet one. Your return depends partly on the SGD-to-USD rate, which can move against you even when the stock rises. And ordinary market risk applies, concentration included.
Check the domicile line on any fund fact sheet before you buy.
Where does a broker fit in?
Plenty of readers searching for the best stock trading app singapore end up comparing fees first, and that’s a sensible place to start. Moomoo is one option. Its Singapore arm, Moomoo Financial Singapore Pte. Ltd., holds a MAS Capital Markets Services licence, according to the company’s site. Its page for US Stocks lists lifetime zero commission on US stocks (terms and other fees still apply), fractional buying from US$5, 24/5 trading, and a regular savings plan for weekly or monthly purchases. It also offers learning resources and an investor community.
No app fixes the concentration issue, though. Whatever you buy first, read its top ten holdings before you click confirm.
Related: BAKO API Forecasting: How Its AI Market Predictions Work
| Disclaimer: This article was written by a guest contributor for informational purposes only and is not financial or tax advice. Details may change, so verify current fees and tax rules with your broker or a qualified adviser before investing. |
