The Sunk Cost Fallacy: Holding Losers Until They Die

I’ve been trading for twenty-three years. I’ve watched fortunes made and demolished. I’ve seen retail traders blow £50,000 accounts on a single Tuesday afternoon. And you know what the most consistent denominator is? Not market conditions. Not volatility spikes. Not even bad luck.

It’s the sunk cost fallacy.

The sunk cost fallacy—that wonderful psychological disability where you throw good money after bad money because you’ve already thrown bad money—is the financial equivalent of pouring petrol on a fire to extinguish it. It doesn’t work. It never has. Yet traders do it every single day, and I’m going to tell you exactly why, and more importantly, how to stop being that idiot.

What Is This Nonsense, Anyway?

Let’s start with the basics, because I’m generous like that.

The sunk cost fallacy is the cognitive bias where you continue investing in something—time, money, emotional energy—because you’ve already invested in it, not because the current fundamentals support that decision. You’re essentially trying to recover losses by doubling down on a losing thesis.

In trading terms: you bought EUR/USD at 1.1050 because the Fed was supposed to be dovish. It wasn’t. Price is now at 1.0950. You’re down two hundred pips. But instead of accepting the loss and moving on, your brain starts playing games with you.

“Well,” you think, “I’ve already lost £800. If I just hold a bit longer, maybe it’ll bounce back. I can’t sell now—that would be crystallising the loss.”

Mate. The loss is already crystallised. Selling doesn’t create the loss; the market did. You’re just deciding whether to compound it.

The London Trading Floor Version

Back in 2009, I worked at a mid-size prop firm in Canary Wharf. There was this trader—let’s call him Dave—who was absolutely brilliant with his analysis. Could read a chart like a poet reads Shakespeare. But Dave had a chronic condition called “I Can’t Accept I’m Wrong.”

Dave had gone long Sterling against the Dollar in early 2008. Brilliant trade at the time. But then the financial crisis hit, and Sterling got absolutely destroyed. Most traders would have cut their losses and moved on.

Not Dave.

Dave held that position for eight months, watching it bleed, adding to it on every “dead cat bounce,” convinced—convinced, I tell you—that Sterling would recover. His argument? “I’ve already lost £30,000. If I sell now, it’s real. If I hold, it might come back.”

Spoiler alert: it came back about eighteen months later. But in the meantime, Dave had added another £50,000 in losses and actually lost his job because the risk committee got wind of his position sizing.

That’s what sunk cost looks like in the wild. That’s what it costs you.

Why Your Meat Computer Is Built For This Nonsense

The human brain didn’t evolve to trade currencies. It evolved to survive on the Serengeti. And on the Serengeti, persistence is often rewarded. If you’re chasing a wildebeest and it runs away, you keep chasing—because sometimes it gets tired and you get dinner.

Trading is the opposite. Sometimes the wildebeest is actually a lion.

Your brain doesn’t know the difference. Your amygdala—that primitive bit that handles fear and attachment—doesn’t understand that the £2,000 you’ve already lost on this position is gone regardless of what you do next. What it does understand is that accepting the loss feels bad, and avoiding that feeling feels good.

So you hold the loser. Your brain releases a little dopamine hit for each tick that goes in your favour (even if it’s just noise). Your portfolio equity bounces around. You tell yourself stories about why you’re right and the market is wrong.

Meanwhile, your actual money is getting murdered.

The Calculator Doesn’t Lie (But You Will)

Here’s where it gets properly cynical.

I’ve built seventeen different forex calculators over the years—pip value calculators, position size calculators, risk-reward calculators. You know what I’ve noticed? Traders use them to justify their trades, not to plan them.

Someone will come to a position size calculator after they’ve already entered a trade at maximum leverage, trying to work backwards to convince themselves it was a reasonable idea. “Well, if I assume a 200-pip stop loss and only risk 2% per trade…”

Nope. The decision was already made emotionally. The calculator is just the excuse.

Here’s what would actually help: Use a calculator before you enter the trade. Lock in your stop loss. Write it down. Then, when you’re in that losing position three hours later and the voice in your head is screaming “JUST HOLD IT A BIT LONGER,” you have a predetermined exit that your emotions can’t negotiate with.

Because your emotions absolutely will negotiate. They’re lawyers, not advisors.

The Cost of “Just One More Bounce”

Let’s do the maths, since I know you love maths when it supports your argument.

You enter a trade with a 1% account risk. Reasonable. Stop loss is tight. Good.

But it hits your stop loss. You didn’t pull the trigger.

Instead, you hold, telling yourself the setup is still valid. The loss doubles to 2%.

Then 3%.

Then 5%.

By the time you finally exit—either because your account is margin called or because the pain becomes unbearable—you’ve turned a 1% controlled loss into a 6% account blowdown.

Do that three times, and you’ve lost 18% of your account to a psychological bias that costs you nothing to avoid.

Just like that, you’re not a trader anymore. You’re a glorified gambler with delusions of competence.

How to Actually Fix This

The solution is stupidly simple, which is precisely why people don’t do it:

Accept that past losses are irrelevant to future decisions.

Make your entries based on confluent signals and risk management. Write down your stop loss in the ticket before you hit buy. When the stop is hit, execute without negotiation.

The sunk cost fallacy thrives in ambiguity. It dies in structure.

Use your forex calculator to plan the trade before you enter—position size, pip risk, reward potential. Lock it in. Then treat that plan like it’s written in stone.

Because the alternative is becoming another cautionary tale that I tell cynical traders over expensive coffee in Covent Garden.

And trust me, there are plenty of us already.

Final Thought

The market doesn’t care about your losses. It doesn’t know or care that you’ve already lost £800 on this position. The market only cares about the next candle, the next data release, the next price action.

Your job is to care about that too. Stop caring about recovering your past losses. Start caring about not creating new ones.

That’s how you survive as a trader. That’s how you actually make money.

Everything else is just noise and ego.

Now close that losing trade.