How to Use Reduce-Only Orders on SOLUSDT Perpetual Contracts?

Understanding Reduce-Only Order Logic

1. A reduce-only order is a trade instruction that exclusively decreases an existing position size without opening new exposure.

2. It cannot increase net long or short exposure — if the user holds no open position, the order will be rejected by the matching engine.

3. The system validates position direction and size before execution, comparing the order’s notional value against the current net position in real time.

4. When placed on SOLUSDT perpetual contracts, the order interacts directly with the on-chain clearing house to ensure atomic position reduction.

5. Execution does not depend on available margin balance beyond what is required to cover potential liquidation penalties during the reduction window.

Execution Flow on Perpetual Protocol V2

1. The user submits a signed reduce-only order through the frontend or API, specifying side (buy/sell), quantity, and leverage level.

2. The Exchange.sol contract verifies the order signature and checks whether the user has an active position of the same direction as the intended reduction.

3. ClearingHouse.sol computes the updated position size and recalculates funding accruals up to the current block using block-based funding logic.

4. If the order would flip the position direction, the contract truncates execution to match only the maximum allowable reduction without crossing zero.

5. After settlement, the updated position size, entry price average, and unrealized PnL are written into the user’s account state in the on-chain ledger.

Margin and Liquidation Implications

1. Reduce-only orders do not trigger margin calls solely due to order submission, as they do not add leverage risk.

2. However, partial reductions may temporarily alter the effective leverage ratio, especially when executed near liquidation thresholds.

3. The protocol applies dynamic maintenance margin calculation based on the post-execution position size and current mark price.

4. If the remaining position falls below the minimum allowed size after reduction, the system may force-close the residual amount at the best available market price.

5. Funding payments accrued prior to execution remain binding and are settled immediately upon order confirmation.

Common Misuse Patterns

1. Attempting to place a reduce-only buy order while holding only a short position results in immediate rejection with error code 0x17.

2. Submitting multiple concurrent reduce-only orders for the same asset pair can cause race conditions in position tracking across tick-level liquidity layers.

3. Using reduce-only orders in combination with stop-market triggers may lead to unexpected partial fills if the stop condition activates during a volatile funding event.

4. Setting limit prices far from index price increases slippage risk, particularly during low-depth periods in SOLUSDT pools.

5. Ignoring the impact of block-based funding settlement means users might underestimate accrued liabilities before initiating the reduction.

Frequently Asked Questions

Q: Can a reduce-only order be canceled after submission but before matching?A: Yes, it remains cancellable until the transaction is included in a block and processed by Exchange.sol.

Q: Does a reduce-only order affect the user’s available balance for other trading activities?A: No, it only modifies position state and does not lock or release collateral unless the reduction triggers automatic margin reallocation.

Q: Is there a minimum size requirement for reduce-only orders on SOLUSDT markets?A: Yes, the minimum executable size is 0.001 SOL, enforced at the contract level in ClearingHouse.sol.

Q: What happens if the reduce-only order crosses the funding settlement boundary during execution?A: Block-based funding ensures all accrued amounts up to the current block height are computed and applied before position update, preserving fee integrity.