What Is a Peg in Crypto? What Depegging Means

What Is a Peg in Crypto: Definition

A peg is a promise about a number. The token ought to be worth a specific unit of some other thing. And it ought to stay worth that specific amount, no matter what the rest of the market is doing. That thing can be US dollar, gold ounce, silver ounce, or pretty much anything else that has a price. So what does pegging mean in crypto, plainly? A token's worth gets tied to an outside marker, and keeps being tied to it (unless something goes wrong).

That marker is often other currency, like US dollar (with USDT, USDC, USD1 tokens), or Euro (with EURC, EURI). There are multiple gold versions too, and a handful of tokens even get pegged to another cryptocurrency.

None of this got invented by crypto, in all actuality. If you’re asking what is pegging in finance, that is a rather old question. Fixed exchange rate setups and currency boards have been pinning one currency onto another for the better part of a century. For instance, Hong Kong has run a dollar peg since 1983. UAE, Qatar, Bahrain, and Saudi Arabia have one, too. So plumbing here is new (through the blockchain), but the idea is borrowed.

What keeps a peg crypto asset sitting near its exact correct price is usually a mix of reserves (if the asset gets too low, company keeping the peg begins buying it, or selling if it gets too high), and also collateral, code, and active traders who find ways to get paid any time the number wanders off.

Sometimes some of this system goes wrong, and that is called de-pegging, which might lead to the trust of the token plummeting, and this can be a catastrophic event. But the rest of the time, assets are tied to each other in price, and that allows for some specific strategies and trades to happen.

Most people asking what is peg in crypto want the same one thing out of it: somewhere more ‘safe’ to park money inside crypto, without having to eat the wild price swings. This is a part of the reason this whole ‘pegged crypto asset’ category exists at all.

Why Most Pegs Target a 1:1 Ratio

One to one is a choice, not a rule. It’s simply easier to grasp that ratio for the human mind. Otherwise, it could be ten to one, or one to forty, without any issues.

Hold a token worth exactly one dollar, and there is nothing to work out. Balance says 4,200, so you are holding 4,200 dollars (if the peg holds). Set the ratio at some 0.37 number instead, and every screen in the whole system turns into a small math problem for a person:

• Pricing reads straight off. Nothing to convert, nothing to double check.

• It lines up with how dollars already sit in the books of every merchant, payment processor and lending desk that might ever touch the token, which counts for more than it sounds like it does.

• And who wants a wallet balance they have to multiply before they can read it?

• Redemption stays clean. One token in, one dollar out, and the arbitrage sum stays easy enough to do while you are still looking at the screen.

One catch worth saying again here is that a 1:1 target is not a 1:1 guarantee. Where the coin actually changes hands gets settled somewhere else completely, minute by minute, by people buying and selling it. Most of the time those two numbers sit close enough that nobody bothers looking. But sometimes they do not, and this mismatch can become a real problem at times.

Peg Mechanism 1: Fiat-Backed Reserves

This is the plain version and by a long way the most used one. An issuer takes in a dollar, parks it somewhere, hands out one token. Bring the token back and the dollar comes out again. Every token out there in circulation is meant to have a real dollar standing behind it.

Parked where, though, that is what decides whether the peg gets through a bad week. A dollar in an uninsured bank account and a dollar in a four week Treasury bill are not the same dollar once everybody asks for their money on the same morning. The bill gets sold in minutes at a known number. The deposit is only as good as whichever bank is sitting on it.

So the line to read is not the headline reserve total. It is what those reserves are made out of, and who is holding them, and how fast any of it turns back into cash. Issuers put out attestations for exactly this reason and the breakdown of what is in there tells you far more than the total ever will.

What can go wrong is a short list. Issuer might not hold exactly what it ‘says’ it holds. The custodian could fail. Redemption might get switched off right at the moment everyone wants it. None of that is a code problem, which is the odd thing about fiat backing, the weak point sits over in the old financial system and not the new one.

Peg Mechanism 2: Crypto-Collateralized

Here the backing is crypto, and since crypto moves, you cannot back a dollar with a dollar's worth of it. You lock up more. Often quite a lot more. Put up 150 dollars of ether, get 100 dollars of stablecoin out, and the spare 50 is sat there to soak up a drop before the position goes bad.

All of it runs on code. Vaults, collateral ratios, liquidations, they all fire on their own, which is why this one only exists on chains that can run smart contracts. Nobody signs off on a liquidation. A number crosses a line and the position gets sold, that is it.

That buffer is not a round figure someone picked for comfort. Chains can get clogged, gas spikes sometimes, and a 150% ratio quietly assumes somebody profitable is watching. Which is also what liquidation penalties are for. They are there to pay the liquidator enough that he bothers turning up at three in the morning.

Strength is that everything sits visible on chain, so anyone can go check the backing themselves instead of waiting on a quarterly report. Weakness is correlation. Collateral and the wider market fall together, and a sharp drop sets off liquidations which then sell into a market that is already going down.

Peg Mechanism 3: Commodity-Backed

Same idea as fiat backing, but different thing in the vault. One token can stand for a fixed amount of a physical commodity, almost always gold, usually a troy ounce or a gram per token. Metal sits in storage and the token is the claim on it.

These get pegged to the commodity and not to a dollar, which is a difference people skip straight past. Gold backed token tracks gold. Gold moves. So the token moves, and calling it stable only makes any sense next to a marker that is also gold.

Redemption window here is rather narrow. Taking physical delivery usually means clearing a minimum measured in whole bars, plus shipping, insurance and a stack of paperwork. Practical effect of that is ordinary holders never redeem at all. Arbitrage gets done by a small group of big participants who can meet the minimum, and the peg holds up because of them and not because of the retail market.

Not everything is peggable this way either. It works for a commodity that is fungible, gradeable and cheap to sit on. Gold qualifies. Live cattle does not.

Peg Mechanism 4: Algorithmic

No vault, no reserve, no custodian. Supply is the only tool in the box. Code watches where the token is trading and it expands or shrinks how many coins are out there to shove the number back toward target. Trading above the peg, mint more. Below it, take some out.

Most designs use a second token to soak up the swing. Burn the stablecoin and mint the volatile partner, or the other way round, and traders get paid a small margin for doing it, because internally the system values the stablecoin at exactly one dollar whatever the market reckons.

Which holds while the partner token is worth something. This is the loop that breaks and it breaks in one direction only. Confidence goes, the stablecoin slips, holders burn it into the partner, partner's supply balloons, its value drops, and the thing that was meant to soak up the fall is now falling quicker than the coin it was supposed to be holding up. TerraUSD in May 2022 is the case everybody points at.

Algorithmic designs are the lightest to run, and also the least forgiving of the ones we discussed here. Nothing outside the system to fall back on. The backing is confidence, and confidence has a habit of leaving all at once rather than in some orderly queue.

How Arbitrage Keeps a Peg Anchored: Step by Step

Reserves and collateral explain why a peg ought to hold. Arbitrage is the thing that actually drags the number back. It is not a safety feature anybody switched on. It is traders picking money up off the floor, and a peg that holds is just the side effect of that.

Say a dollar pegged token slips to 0.985 on an exchange.

1. A trader buys 100,000 tokens at 0.985 and pays 98,500 dollars for the lot.

2. Those tokens go back to the issuer, who is on the hook for one dollar each.

3. 100,000 dollars comes back out. Gross gain of 1,500 dollars, before fees and before whatever the transfer itself costs to do.

4. None of that buying happened quietly, though. Every desk running the same play is lifting the order book at the same time and the price climbs back toward one.

Runs the other way too. At 1.02 the profitable move flips round: mint new tokens at a dollar, sell them at 1.02, and that selling drags the number back down again. Both directions, same logic. Gap is the payment.

But redemption door has to be open and it has to work. Close it, slow it, or make markets doubt it, and the arbitrage here stops being a free trade, and turns into a risky bet. Same arithmetic also shows up in cross chain arbitrage, where what a trader is really getting paid for is the wait between venues. How wide a gap stays open comes down to fees plus how long capital sits locked in transit, which is why a token that settles in minutes holds a tighter peg than one that settles in two days, even when nothing else about the two designs is any different at all.

Comparing the Four Mechanisms by Stability

Laid out next to each other, the four are not four flavors of one thing. They break in different places, for different reasons, on different clocks.

Reserve makeup, redemption terms and availability all shift over time, so the issuer's own current paperwork is worth a read rather than assuming any row up there is fixed.

Ranked bluntly: fiat backing is the steadiest of the four right up until the weak link turns out to be a bank. Crypto collateral is transparent and handles on chain trouble better, while staying wide open to the same selloffs as everything else. Commodity backing is stable against its commodity and nothing else. Algorithmic designs have got the best story and the worst record.

What Depegging Means

A ‘depeg’ is what it sounds like. Price leaves its intended target. If it happens for long enough so the markets start to notice, it can become a huge problem. Nine tenths of a cent off par on a dollar pair during a quiet Sunday can be chucked off as noise. But four cents off across every venue for a whole day is a different animal.

Two things tell you which one you are looking at, and they are depth and duration. A short gap on one exchange usually just means liquidity was thin there. A wide gap holding everywhere, while questions go round about the reserves, means the market is pricing in something real.

Causes, real cases and the warning signs traders watch out for are handled properly in this breakdown of stablecoin depegging, the March 2023 USDC episode included, plus how it got resolved. That is where to go if the risk side is what you came for, since this piece is about how the tie gets built and not so much how it snaps.

Conclusion

Four mechanisms and one question that works on all of them. When you want your dollar back, who is standing on the other side of that trade, and can they actually pay it? With fiat backing it is an issuer and a bank. With crypto collateral, a liquidator and a vault. With gold it is a vault operator holding you to a minimum bar size. With an algorithm it is nobody in particular, which is the entire problem right there. Peg is only ever as good as the answer to that one question.

Disclaimer: Trading involves risks of capital loss and may not be suitable for all investors. This article is for informational purpose only and does not constitute financial advice.