Exchange Margin Tiers and Insurance Funds
Crypto exchanges cap how much leverage a position can use as it grows, and keep a shared insurance fund to absorb the losses left behind when a liquidation can't be closed out at a fair price.
Prerequisites: Perpetual Futures and Funding Rates, Liquidations and Cascade Risk
A trader wants to put on a $50 million position with 100x leverage. If the exchange allowed that, a 1% adverse move would wipe out the margin instantly, and the exchange would likely be unable to close the position at a price anywhere near where it triggered — leaving a loss with nobody left to absorb it. So exchanges don't offer flat leverage regardless of size. They shrink the maximum leverage as a position grows, and they keep a pooled buffer to absorb the losses that liquidations still can't fully cover.
Margin tiers cut the maximum allowed leverage in steps as a position's notional size increases, because larger positions are harder to close without moving the market. The insurance fund is a pool, built from liquidation fees, that covers the gap when a liquidated position gets closed at a worse price than its bankruptcy price — protecting other traders from having to eat that loss.
Why leverage shrinks with size
A small position can be closed almost instantly at close to the current price; a huge one moves the order book as it's unwound, so it needs a bigger cushion before it's forced to close. Exchanges implement this with a margin tier table: as a position's notional value crosses set thresholds, the maximum leverage allowed drops and the maintenance margin requirement rises.
The insurance fund
When a position hits its liquidation threshold, the exchange's engine tries to close it in the market at or near the bankruptcy price — the price at which the position's remaining margin hits exactly zero. In fast, thin markets the actual closing price can be worse than the bankruptcy price, leaving a shortfall. The insurance fund, built up over time from a slice of liquidation fees on positions that were closed favorably (better than bankruptcy price), covers that shortfall so the loss doesn't fall on the counterparty who was on the winning side of the trade.
Worked example
A trader's long position has a bankruptcy price of $60,000. The liquidation engine tries to close it but the market gaps down fast, and the position is actually closed at $59,700 — a further $300 per unit of exposure worse than bankruptcy price. That shortfall, multiplied across the position size, is paid out of the insurance fund rather than clawed back from the trader on the other side. Contrast that with a second, orderly liquidation the same day: a position with bankruptcy price $60,000 is actually closed at $60,050 — better than bankruptcy price, because there was still a margin cushion left when it was caught. That $50-per-unit surplus is swept into the insurance fund, replenishing what the first liquidation drew down.
What this means in practice
The insurance fund's balance is a real signal of exchange health during stress: a fund that's shrinking fast during a volatile period means liquidations are consistently closing worse than bankruptcy price, and if the fund is ever exhausted, the exchange has to fall back on auto-deleveraging, force-closing profitable counterparties' positions instead. Margin tiers and the insurance fund together are what let an exchange offer high leverage on small positions without that leverage becoming a systemic hole when a large position blows up.
A deep insurance fund is not a guarantee against losses reaching traders directly — it's a buffer with a bottom. During a genuinely violent, correlated move, insurance funds have been drained to zero on real exchanges, forcing auto-deleveraging of profitable positions that had nothing to do with the original liquidation.
Related concepts
Practice in interviews
Further reading
- Binance Futures, 'Leverage and Margin'
- BitMEX, 'Insurance Fund Explained'