EMX employs cross margining across all accounts. Both deposited collateral and unrealized PNL (the Net Liquidation Value -- NLV) will be available for use to satisfy margin requirements. The NLV must be greater than the initial margin of a contract in order to enter a long or short position in that contract. If the NLV decreases below the liquidation level required by open positions, a forced liquidation will occur. The NLV (deposited BTC collateral and unrealized PNL) is valued in USD, therefore fluctuations in BTC USD prices will increase or decrease margin that is available for trading. Note: "available for trading" and "available for margin" mean the same thing.
Example (with the initial margin for one BTC USD Futures contract at $100):
- Jessie deposits 20 BTC. BTCUSD is currently $5000, so Jessie has $100,000 available for trading.
- Jessie buys 100 BTCUSD futures, requiring $10,000 for initial margin (100 * $100 initial margin requirement). She now has $90,000 remaining as available for trading ($100,000-$10,000).
- BTCUSD goes up to $6,000. Jessie now has $220,000 in her account ($100,000 in unrealized PNL, and $120,000 from deposited BTC). $10,000 is still required for initial margin, so her total funds available for trading is $210,000.
Initial margin requirements for all contracts can be found here: Fees and Contract Specifications