In a funding rate arbitrage, the perpetual contract leg can get liquidated first, leaving a naked spot position exposed to the market. This isn't a strategy failure; it's a margin allocation mistake — you didn't leave enough buffer on the contract side and didn't treat unrealized profits on the spot leg as a usable safety cushion.
Here are 3 steps to reallocate margin after discovering a liquidation.
Prerequisite: Identify Why the Perpetual Contract Was Liquidated
Before topping up margin, confirm exactly why the liquidation occurred:
Reason A (Sharp price movement): The perpetual contract price moved sharply against your position in the short term, hitting the liquidation level. Even if the overall arbitrage position's net value didn't change much, the margin on the contract side got wiped out.
Reason B (Margin rate set too low): You used too much leverage or deposited too little margin when opening the position, leaving insufficient safety distance.
Reason C (Funding rate direction changed): The funding rate flipped from you receiving payments to you paying them. Continuous outflows eroded the margin balance.
Different causes require different adjustments. First, check your contract account's "Order History" or "Liquidation Records" to confirm which one happened.
Step 1: Confirm the Size and Direction of Your Current "Naked Position"
After the perpetual leg is liquidated, the spot leg remains, forming an unhedged directional position. First, figure out exactly how much risk you're now exposed to.
What to do: Calculate the notional value of the current spot position and its unrealized profit/loss.
How to do it:
Open your spot account and record the coin and quantity you currently hold.
Calculate the total spot value at the current market price: Total spot value = Position quantity × Current price.
Compare with the spot cost price to determine the unrealized PnL amount.
This "naked position" is the most urgent risk you need to address. If the market keeps moving against you, the spot position will bear the full brunt of the volatility.
Completion criteria: You know exactly how much spot you are "naked" on, and how much the spot position would lose if the price swings another 10%.
Step 2: Calculate the "Minimum Safe Margin" Using Three Tiers
At its core, a liquidation happens because margin can't cover the price movement. How much to add isn't a random guess — you need a quantifiable standard.
What to do: Use three tiers to calculate the minimum margin you need to add.
How to do it:
First, define two reference prices:
Current price at which you plan to re-enter a short: P_current
Your spot cost price (or the maximum adverse price you're willing to tolerate): P_stop
| Safety Tier | Margin Requirement | Applicable Scenario |
|---|---|---|
| Conservative (Recommended) | 5%-10% of notional value | Highly volatile altcoins, or when funding rates are very high |
| Standard | 3%-5% of notional value | Major coins (BTC/ETH) with relatively mild volatility |
| Minimum | 1%-2% of notional value | Only for extremely low-volatility environments; not recommended for arbitrage |
Formula: Required margin = Spot notional value × Safety tier percentage
Example: You hold $10,000 worth of spot and plan to reopen an equivalent short to hedge. With the conservative tier at 5%, you need at least $500 in margin on the contract side (if using 10x leverage, a $10,000 notional value requires only $1,000 in margin, but the 5% here refers to 5% of notional value, i.e., $500, well above the minimum margin requirement).
Completion criteria: You have a specific number — the amount of margin you need to transfer into the contract account.
Prerequisite: You need enough available stablecoin funds to top up the margin. If your account is out of money, you may need to transfer some funds from the spot account (this reduces the spot position, breaking the equal-value hedge, and requires a simultaneous adjustment).
Step 3: Re-Establish the Hedge and Perform the "Three-Account Check" for Margin Allocation
After topping up the margin, reopen a short to rebuild the hedge. But this time, make sure the allocation is solid.
What to do: Execute two actions at the same time — reopen the short and transfer the required margin into your contract account in one go.
How to do it:
Reopen a perpetual short with a notional value equal to your spot position.
The amount of margin transferred in = the result calculated in Step 2.
Complete the following "Three-Account Check":
Spot account: Confirm spot quantity hasn't changed.
Perpetual contract account: Confirm the short is open and its notional value matches the spot position.
Contract margin balance: Confirm available margin balance ≥ required margin.
If the platform supports isolated margin mode, it's recommended to place this arbitrage position under isolated margin, not cross margin. In isolated mode, the margin only backs this one position and won't be drawn down by losses elsewhere. Cross margin is more capital-efficient, but problems in other positions can drag down this arbitrage trade.
Completion criteria: All three account checks pass. The "maintenance margin rate" in the contract account is at least 20% above the minimum requirement.
Common failure point: After adding margin, only a small short is opened that doesn't cover all the spot. This is a "partial hedge" that leaves directional exposure — you're effectively betting on direction instead of doing arbitrage.
Risk reminder: Even after re-hedging, if the market continues to move sharply, the contract side can still hit the liquidation price again. We recommend setting an alert at least 20% before the liquidation price, so you can manually add margin early rather than waiting for the system to liquidate. Also, the funding rate can suddenly flip negative, turning you from a receiver into a payer, which slowly grinds down the margin balance.
How to Confirm Your Operations Are Correct?
After performing the above steps, open the "Positions" page in your contract account and check these three data points:
Liquidation price: Is the gap to the current price more than 30%? If it's below 20%, the safety buffer is insufficient — add more margin.
Margin rate: Is it at least 20% above the minimum requirement?
Notional value match: Is the short position's notional value ≈ the spot position's value? Deviation should not exceed ±2%.
If all three pass, this arbitrage position is safe again. Write down the liquidation price and check the margin balance at least once a week, especially around funding rate settlements — the margin balance changes as fees are paid or received.
FAQ
Q: After liquidation, my spot position is still there. Can I just sell the spot and end the arbitrage without adding margin? A: Yes, that's one of the standard ways to exit the arbitrage. The path is: close the remaining short (if any) while selling the spot. But note, if you don't sell immediately after the liquidation and the market continues to fall, the spot position's loss turns into a realized loss. In contrast, topping up margin and reopening a short means you continue the strategy, waiting for funding fee income to offset the loss; closing out means you cut your losses and exit. Both are reasonable — it depends on your judgment of the coin's future funding rate.
Q: When adding margin, should I factor in the profits from the spot leg? A: Yes, you need to consider it. Your total account net value = spot unrealized PnL + contract unrealized PnL (after opening the short) + contract margin balance. The money to top up margin can come from the spot account or from external sources. But if you transfer funds out of the spot account, it changes the spot position value, causing a mismatch with the short, so you would need to adjust the short size accordingly. It's best to add margin with stablecoins transferred from external sources and leave the spot position untouched.
Q: Different platforms have different funding rate settlement frequencies. Does that affect margin allocation? A: Yes. Binance settles every 8 hours, Hyperliquid every 1 hour. The higher the settlement frequency, the more frequent the funding fee payments, causing greater fluctuations in the margin balance. When doing arbitrage on high-frequency settlement platforms like Hyperliquid, you need a larger margin buffer, because the hourly funding inflows/outflows continuously impact available balance.
