Open any investing article and you’ll be hit with a wall of three-letter acronyms within the first paragraph. ETF, REIT, ESG, IPO, P/E — it sounds like alphabet soup with worse table manners. The truth is you only need to understand four things to invest sensibly: stocks, bonds, ETFs, and index funds. Everything else is a variation on those four.
This is Part 2 of 6 in our Investing 101 series. Last week we covered the three prerequisites you need before investing. Today: what you actually buy.
Stocks: Owning a Slice of a Company
A stock (or “share”) is exactly what it sounds like — a small ownership stake in a real, operating business. Buy one share of a company that has issued a million shares, and you own one-millionth of it. You’re entitled to a proportional slice of its profits and its assets.
Where the returns come from
Stocks make money for owners in two ways:
- Price appreciation — the company becomes more valuable over time, so the share price rises
- Dividends — many established companies pay out a portion of their profits as cash to shareholders, usually quarterly
In the very long run, the historical real return on broad stock markets has been around 6–7% per year after inflation. That number hides enormous year-to-year variation: stocks routinely fall 20%+ in a bad year and rise 20%+ in a good one. The investment return calculator lets you play with different assumptions to see how the maths plays out.
The trade-off
Stocks have the highest long-term returns of any major asset class. They also have the most volatility. If you can’t emotionally handle watching your portfolio drop 30% in a recession without selling, you shouldn’t be 100% in stocks — which is exactly what we’ll explore in Part 3 on risk tolerance.
Bonds: Lending Money for Interest
A bond is a loan. When you buy a bond, you’re lending money — to a government, a city, or a company — in exchange for a promise to pay you back at a specific date, with regular interest payments along the way.
A simple example: you buy a 10-year government bond with a face value of €1,000 and a 3% coupon. The government pays you €30 a year for ten years, then gives you your €1,000 back at the end.
Where the returns come from
Mostly the interest payments (“coupons”). Bond prices do also move up and down based on interest rates and creditworthiness, but the day-to-day price movement is far smaller than stocks.
The trade-off
Bonds return less than stocks over long periods — roughly 1–3% real annual returns historically — but they’re much steadier. In a year when stocks fall 25%, a portfolio of high-quality bonds might be flat or even up slightly. That stability is the whole point of owning them: bonds smooth out the ride, especially as you get closer to needing the money.
Types of bonds (briefly)
- Government bonds — issued by national governments. Lowest risk, lowest yield. US Treasuries, German Bunds, UK Gilts.
- Corporate bonds — issued by companies. Higher yield, more risk (the company could default).
- Municipal bonds — issued by cities/states. Often tax-advantaged depending on jurisdiction.
- High-yield (“junk”) bonds — riskier corporate bonds with higher coupons. Behave more like stocks than bonds in a crash.
For most beginners, “bonds” effectively means a single broad-market bond ETF that holds thousands of bonds at once. Which brings us neatly to the next concept.
ETFs: Buying a Bundle in One Click
An ETF (exchange-traded fund) is a basket of many securities — stocks, bonds, or both — that trades on a stock exchange like a single share. Buy one share of a global stock ETF and you instantly own a tiny piece of two or three thousand companies across dozens of countries.
This is roughly the most important innovation in retail investing in the last 50 years. Before ETFs, building a diversified portfolio meant either (a) buying dozens of individual stocks (expensive, complicated) or (b) using a mutual fund (often expensive in fees, only tradable once per day).
ETFs solved both problems. They’re cheap (the largest cost less than 0.10% per year), liquid (trade all day like a stock), and instantly diversified.
What “diversified” buys you
Diversification means that no single company’s collapse can sink your portfolio. If you own one stock and it goes bankrupt, you lose everything. If you own a global ETF holding 3,000 companies and one of them goes bankrupt, you lose 0.03%. Mathematically equivalent to “barely noticing.”
We cover the trade-offs of different fund types in detail in our index funds vs ETF vs mutual funds guide.
Index Funds: The “Just Buy Everything” Strategy
This is where it gets philosophically interesting. There are two ways an ETF (or any fund) can be managed:
- Actively managed — a human fund manager picks which stocks to buy, trying to beat the market
- Passively managed (index fund) — the fund simply buys every stock in a defined “index” (like the S&P 500 or MSCI World), no stock-picking, just mechanical replication
An index fund is just a fund that follows an index. Most modern index funds are structured as ETFs, but you can have index mutual funds too. The terms “index fund” and “passive ETF” are nearly synonyms in practice.
Why this matters enormously
Decades of research show that most active fund managers fail to beat their benchmark index after fees. Roughly 80–90% of active funds underperform their passive equivalent over 15+ years. The maths is simple: index funds charge 0.03–0.10% per year; active funds charge 0.5–1.5%. To beat the index after fees, an active manager needs to be skilful enough to overcome that headwind, and the data says very few are.
This is why beginner advice almost universally points to broad index funds. They’re cheap, simple, diversified, and they win most of the time by losing less. We’ll come back to this debate in Part 5 (active vs. passive).
How These Pieces Fit Together
Here’s the short version of how a typical beginner portfolio is built:
- Pick a stock-to-bond ratio based on your risk tolerance (Part 3).
- Fill the stock portion with one broad index fund ETF holding global stocks.
- Fill the bond portion with one broad index fund ETF holding global bonds.
- Done. Add money regularly. Rebalance occasionally.
That’s not an oversimplification. Some of the most well-regarded portfolios in the world for individual investors are literally two ETFs. We’ll show three concrete examples in Part 4. Track everything in the portfolio tracker once you’ve made your first purchase.
Affiliate placeholder — ETF screener / broker-with-zero-commission-ETF-trades section will go here.
The Concepts Worth Knowing (One Sentence Each)
A short glossary so the rest of the series reads cleanly:
- Dividend — cash paid by a company to shareholders, usually quarterly.
- Yield — the annual income (dividends + interest) from an investment, expressed as a percentage of its price.
- Expense ratio (TER) — the annual fee a fund charges, expressed as a percentage. 0.10% is cheap, 1% is expensive.
- Volatility — how much the price moves up and down over time. Higher volatility = bumpier ride.
- Diversification — spreading money across many different investments so no single one can sink you.
- Asset allocation — the mix of stocks, bonds, and other asset classes in your portfolio.
Action Items for This Week
- Look up two ETFs. Search for one broad global stock ETF (try “MSCI World ETF” or “VT”) and one broad bond ETF. Read their fact sheets. Don’t buy anything yet — just look.
- Note the expense ratios. Anything under 0.20% per year is good for a broad index fund.
- Read one fund’s holdings. Most fund providers publish a full list of what the fund owns. Scrolling through 1,500 companies makes “diversification” feel real in a way that no explanation can.
Next week, in Part 3, we’ll figure out your personal mix of these building blocks — by sorting out one of the most misunderstood concepts in investing: risk tolerance.