The question
"I have some savings. Do I keep it in cash where it's safe, or invest it where it can grow? What's the actual difference?"
The idea
- Cash and stocks do different jobs. Cash pays a small, steady return and almost never loses value. Stocks have grown more over long periods, but they can drop sharply, and you never know when. So the real question is not "which one wins?" but "when will I need this money?" Money you need soon wants steadiness. Money you won't touch for years can ride out the drops.
Worked example
We'll compare two real ETFs from lesson 2:
- BIL holds Treasury bills, very short loans to the US government. It behaves like cash.
- SPY holds the 500 or so large US companies in the S&P 500. It behaves like the stock market.
We'll use total return: how much the money grew, counting price changes plus any interest or dividends paid, as if they were put back in.
Part 1: the full year, Nov 10, 2025 to Nov 10, 2026.
Step 1. BIL returned +3.7% (3.67% unrounded). $10,000 × 1.0367 = $10,367.
Step 2. SPY returned +11.2% (11.23% unrounded). $10,000 × 1.1123 = $11,123.
Step 3. The gap: $11,123 − $10,367 = $756 more in SPY over the year.
Part 2: just the last month, Oct 9, 2026 to Nov 10, 2026.
Step 4. BIL returned +0.3%: $10,000 became about $10,032.
Step 5. SPY returned −3.7%: $10,000 became about $9,632. That is a $368 drop in one month.
Step 6. On Nov 10, 2026, SPY stood 3.7% below its high of Oct 6, 2026. BIL had no such fall.
What it means: over the year, stocks paid more. But someone who put money into SPY a month earlier and needed it on Nov 10, 2026 got back less than they put in. The year's extra $756 came with the risk of that drop.
The common mistake
"Stocks returned more, so cash is a waste." Over a year, maybe. But a return only helps if it is there when you take the money out. If you'll need it for rent, a deposit or an emergency in the next few months, a 5% drop in the wrong month can hurt more than a few percent of extra growth helps. The opposite mistake is just as common: keeping money for a goal 20 years away in cash, because a month like October 2026 felt scary.
Check your understanding
Pick an answer to see why. Two of three right passes the lesson.
1. What does "total return" count?Answer: C. Price changes plus interest and dividends, put back in. total return adds everything the money earned. Not A: price alone leaves out the interest a cash fund pays, which is nearly all of what BIL earns.2. Over the month to Nov 10, 2026, what happened to $10,000 in SPY?Answer: B. It fell to about $9,632. SPY returned −3.7% that month. Not A: $11,123 is the one-year result, a different window.3. Maria is saving for a house deposit she will pay in four months. Using this lesson's idea, which fact matters most to her?Answer: B. SPY fell 3.7% in a single month, while BIL rose. with only four months, a drop like that could leave her short when she needs the money. Not A: a higher one-year return doesn't help if the fall lands right before she pays.
Takeaways
- Match the money to the date you need it: soon means steady, years away can ride the drops.
- Look at more than one window. One year and one month can tell opposite stories.
- Compare any two funds on ETFIQ to see both their returns and their falls.