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Matched Book Margin (MBM) is the Tplus leverage model. It keeps one spot book for both spot and leveraged flow:
  1. Default: leverage is spot margin - a real borrow against real holdings.
  2. Optimization: opposite-side leveraged exposure in the same asset offsets.
  3. Remainder: only the unmatched skew uses depositor liquidity.
That gives Tplus much of the capital efficiency of perpetuals while keeping positions spot-fungible: composable with external venue spot markets.

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Matched exposure

Borrowing is only needed for net exposure. For a leveraged long and short in one asset:
  • The long holds the asset and owes USD.
  • The short holds USD and owes the asset.
Each covers the other: the long’s asset satisfies the short’s asset debt, and the short’s USD satisfies the long’s USD debt. The matched portion draws no depositor funds. Matched exposure is also the portion that can be auto-delevered internally. ADL is not continuous matching; it runs during backstop clearing when the backstop falls below initial margin, force-closing profitable opposite-side exposure instead of sourcing new liquidity from the market. See Liquidations.

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Skew

Skew is the unmatched remainder: the net directional exposure with no offsetting counterparty, |aggregate longs - aggregate shorts| per asset. Only the skew draws a real borrow:
  • Net-long skew borrows USD at the quote borrow rate.
  • Net-short skew borrows the asset at its base borrow rate.
For example, 100M USD of leveraged longs and 60M USD of leveraged shorts leaves 60M USD matched and 40M USD of net-long skew funded by USD deposits. Skew is the only exposure that consumes deposit liquidity and carries market-impact liquidation risk, so MBM is built to keep it small and clear it cheaply.

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Funding and stress premiums

Funding manages skew. A balanced book pays zero funding. Inside a per-asset deadzone the rate is zero; beyond it the rate grows with the square of the skew. A separate premium component applies when orderbook impact prices deviate from the oracle. Formulas and parameters: Funding rates. Ordinary flow imbalance should be carried as skew rather than a price premium. Under extreme market conditions that can fail: if the deposits needed to fund skew are depleted, Tplus can still trade at a premium or discount until new deposits, opposite-side flow, settlements, or liquidations clear it.

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Compared with perpetuals

Perpetuals get capital efficiency by making every position synthetic. MBM makes matched exposure synthetic-like; unmatched exposure is standard spot margin.

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Clearing skew

Only the net skew, not gross volume, needs external liquidity. Settlements and cross-margining allow skew to unwind without the protocol warehousing large inventory:
  • Funding pulls in underweight-side leverage flow.
  • Settlements close skew and liquidation flow against external spot liquidity.
  • Cross-margining lets makers run offsetting basis trades with twice the capital efficiency.