Hyperliquid has introduced a portfolio margin system on its testnet, currently in the pre-alpha phase. This new system consolidates users' spot and perpetual trading accounts, enhancing capital efficiency and automatically generating interest on unused borrowable assets. Initially, only USDC can be borrowed with HYPE as the sole collateral, with plans to support USDH and BTC in the future. The system allows users to engage in collateralized arbitrage, offset PnL, and reduce liquidation risk, while integrating with lending protocols in the HyperEVM ecosystem.