The first time someone told me their profitable short got closed for them, in a violent down move, exactly when they wanted it open the most, I assumed they had misread their own order history. They had not. The exchange did it, on purpose, and it was working as designed. That is the part almost nobody explains up front. When you trade perps, there is a chain of events that runs after a liquidation goes wrong, and the last link in that chain can reach into your account whether you are up or down.
So this is the machinery. What happens when a liquidation cannot be filled at a price that keeps the losing account solvent, why an insurance fund exists, and how auto-deleveraging picks which winning traders to close. None of it is exotic once you see the order it runs in. It just tends to stay invisible until the one day it costs you.
When a liquidation goes bankrupt
Start with a normal liquidation. A trader is over-leveraged, the market moves against them, and their margin drops below the maintenance requirement. The exchange takes over the position and tries to close it in the market. On a calm day this fills near the bankruptcy price, the account goes to roughly zero, and nobody else is affected. That is the happy path and it is most of the time.
The problem is the day that is not calm. In a fast move, the liquidation engine tries to sell into a book that is falling faster than it can dump size. It fills below the price at which the account's collateral is fully gone. Now there is a hole. The losing trader owed the system a certain amount and the forced sale recovered less than that. Someone has to eat the difference, because the trader on the other side of that position is owed their full profit and expects to be paid.
This is the moment the whole system is built around. A perpetual exchange is a closed loop. Every dollar a winner makes came from a loser. When the loser's account cannot cover what they lost, the winner's profit is suddenly unfunded. The insurance fund is the first thing that stands in the gap.
What the insurance fund actually does
The insurance fund is a pool of capital the exchange keeps specifically to absorb these bankruptcy shortfalls. It gets fed on the good days. When a liquidation fills better than the bankruptcy price, that surplus goes into the fund instead of back to the liquidated trader. Over time, in normal conditions, the fund grows because most liquidations are handled at a small surplus. Then on a bad day it pays out to cover the holes.
Think of it as the buffer that lets winners get paid even when losers default. As long as the fund has capacity, an under-water liquidation is invisible to everyone except the person who got liquidated. The counterparties keep their full profit, the fund quietly shrinks, and life goes on. A healthy fund is doing its job precisely when you never notice it.
A few things worth knowing about these funds as a trader. They are not infinite, they are not a guarantee, and their size is public on most venues. When a fund is large and stable relative to open interest, the venue can weather rough liquidations without touching anyone else. When it is small, or draining fast during a crash, you are closer to the point where it fails. That is the trigger for the thing people actually fear.
Auto-deleveraging: when the buffer runs dry
Auto-deleveraging, ADL, is what happens when the insurance fund cannot cover the shortfall. The exchange still has to close that bankrupt position and it still has to keep the book balanced. So it forcibly closes opposing positions on the other side of the market to make the two sides net out. Those opposing positions belong to traders who are, by definition, on the winning side. They get closed at the bankruptcy price of the liquidated account, at that moment, ready or not.
Read that again slowly, because it is the whole point. ADL closes profitable positions. You did nothing wrong. You had margin to spare, you were on the right side of the move, and the engine closed you anyway because it needed your position to offset a default it could not otherwise fund. There is no appeal. It is a socialized-loss mechanism dressed up as a matching operation.
The obvious question is who gets picked. Exchanges rank candidates in an ADL queue, and the ranking is not random. Broadly, they sort by profitability and by leverage. The traders who are the most profitable and using the most leverage sit at the front of the queue. The logic is that these accounts have gained the most from the move that just bankrupted someone, so they are first in line to give some of it back. If the first account in the queue does not fully offset the bankrupt position, the engine works down the list until the two sides balance.
How to read your own ADL indicator
Most serious perp venues show you an ADL indicator on each position, usually a small row of lights or a bar with a few segments. It is telling you where you sit in that queue for that market. More lit segments means you are closer to the front, so you would be closed earlier if ADL fires. A fully lit indicator on a big winning position is the exchange quietly telling you that in a bad enough event, you are near the top of the list.
Here is how I actually use it, and a rough workflow you can copy:
- Check the indicator on any position that has moved deep into profit, especially in a market that is trending hard. Profit plus high leverage is what pushes you up the queue.
- If it is lit up and the trade thesis is mostly played out, take partial profit. Realizing gains drops your position down the ranking because you are no longer sitting on as large an unrealized win.
- Cutting leverage on the position helps too. Lower leverage moves you back in the queue even if you keep the size, because the ranking weighs both.
- Watch the insurance fund on the venue during genuine crash conditions. A fund draining fast toward zero is the environment where ADL actually triggers. On a normal day the indicator is just information.
The failure mode I have watched people walk into is treating a monster winning short during a crash as a set-and-forget position. That is the exact profile ADL is hunting for. Deeply profitable, highly leveraged, on the opposite side of the accounts blowing up. You can be completely right about direction and still get pulled out at the worst possible moment, then watch the move continue without you. The indicator was flashing the whole time.
How to keep your exposure down
You cannot opt out of ADL. Every perp venue that has an insurance fund also has some form of it, because the closed-loop math does not leave another option once the fund is empty. What you can do is stay out of the front of the queue. Lower leverage, take profit into strength rather than holding for the absolute top, and do not run your biggest most-leveraged winner naked through a market-wide liquidation cascade. Spreading size across venues helps too, since each has its own fund and its own queue, so one venue's bad day does not necessarily reach all of your risk.
It also pays to know the health of the venue before you size up. Fund size relative to open interest, historical behavior in past crashes, how transparent they are about the ADL ranking. When we built the execution routing at Blockcircle across a lot of exchanges, this venue-level risk was a real input, because the same position can carry very different tail risk depending on how well capitalized the venue is behind it. That is not something the price chart ever shows you.
The one habit I would leave you with is simple. Every time a position becomes a real winner, glance at the ADL indicator before you go do anything else. It costs you two seconds and it tells you exactly how much the exchange is eyeing your profit. Most days it means nothing. The day it means something, you will be very glad you looked.