Trading fees and realized P&L on Gemini Crypto derivatives are still charged in GUSD. As users can trade derivatives without any GUSD in their account, the Negative Balance feature gives customers the choice as to how any negative GUSD balance would be treated. 

• If the Negative balance feature is disabled, then as soon as any negative GUSD balance is created (for example because the user incurs a fee on a derivative trade) some cross collateral assets would be liquidated to generate sufficient GUSD to cover this negative balance. The user will incur a liquidation fee for this transaction. 
  
  
• If the Negative balance is enabled, the user can maintain a negative balance up to -5,000 GUSD before any cross collateral assets will be liquidated to cover (part of) the negative balance. Running a negative balance may incur a management fee. However, the user can deposit funds at any time before the next reconciliation time (every 12 hours, 8am and 8pm UTC). in order to clear the negative balance and not incur any fee.

Note: Negative Balance only applies to GUSD.