Most costly investing mistakes aren't exotic — they're a handful of very human errors that repeat across generations of new investors. Knowing them in advance won't make you immune, but it makes them easier to catch.
Trying to time the market
Waiting for the "perfect" moment to invest, or jumping in and out trying to dodge falls, tends to backfire. Reliably predicting short-term market movements is something even professionals struggle to do consistently. For most people, investing regularly over time — sometimes called pound-cost averaging — sidesteps the impossible task of timing it perfectly.
Panic-selling in a downturn
When markets fall, the instinct to sell and "stop the bleeding" is powerful — and it's how paper losses become real ones. Falls are a normal part of investing over a long horizon; selling during one locks in the loss and means missing any recovery. This is why matching your investments to a timeframe you can stick with matters so much — see risk and diversification.
Ignoring fees
Charges feel small — a fraction of a percent here and there — but because they compound against you over decades, they can quietly consume a meaningful chunk of your returns. Comparing the ongoing charges of funds and platforms is one of the few things genuinely within your control. Our guide on index funds vs individual shares touches on why lower-cost passive funds appeal to many.
Investing money you'll soon need, or before clearing expensive debt
Two ordering errors: putting money you'll need within a few years into investments that could fall, and investing while carrying high-interest debt whose guaranteed cost likely exceeds your expected investment return. Our guide on saving vs investing first lays out a sensible order.
Not starting at all
Finally, the quietest mistake: waiting indefinitely to feel "ready." Because of how compounding rewards time, a modest start now often beats a perfect plan years later. You don't need to get everything right to begin — you need to begin, then improve as you learn.