Aster said it will start charging interest on negative balances in USDT and USD1 under its Multi-Asset Mode from 10:00 UTC on April 9, 2026. The fee will not apply immediately to every deficit. It starts only when the balance in either asset falls below -1,000, and the threshold is calculated separately for USDT and USD1.
Hourly interest applies only to the amount beyond the free threshold
Under the new rule, users can carry a negative balance up to -1,000 in either asset without triggering the charge. Once that level is exceeded, interest accrues every hour on the portion below the free limit. Aster’s example shows that if a user holds a -2,000 USDT balance and the hourly rate is 0.000457%, the charge applies only to the extra 1,000 USDT. That produces an hourly fee of 0.00457 USDT.
The platform also said the current annualized rate is about 4%. For traders, though, the hourly number is likely to matter more, since it feeds directly into the cost of keeping a margin deficit open over time.
Shared collateral stays in place, but deficit costs become explicit
Aster Multi-Asset Mode is designed around shared collateral across positions in a cross-margin structure. The account is assessed more like a single portfolio than a set of isolated trades, with gains, losses, and collateral working together. That can improve capital efficiency. It also means negative balances can remain part of normal trading activity rather than an immediate exception.
This is where the update changes the economics. A negative balance is no longer just an account condition; beyond a certain point, it becomes a carrying cost. Heavy leverage users may need to fold that cost into day-to-day risk controls, while smaller accounts may feel less pressure because of the free buffer.
The rule may change how traders manage margin inside the platform
The announcement does not point to a broader market shock, but it could alter behavior inside Aster’s trading system. Users relying on USDT and USD1 as working margin assets may choose to rebalance sooner, move collateral earlier, or reduce leverage before hourly charges build up. The core structure of Multi-Asset Mode remains the same. What changes is that deeper negative balances now have a defined price.
The move also fits a wider pattern in crypto derivatives. Platforms are getting more specific in how they price account risk, using ongoing charges alongside liquidation rules and collateral valuation methods. Aster’s message is straightforward: negative balances are still possible in Multi-Asset Mode, but from April 9, keeping a deeper deficit in USDT or USD1 will no longer be free.