SLAB DOCS

SLAB is card-backed lending on Ethereum. You vault a physical graded card, it gets marked to real sales comps, and you borrow USDC against it. Lenders supply USDC and earn the interest. When a loan crosses the liquidation line, the slab is auctioned to other holders.

Overview

The protocol is four contracts:

SlabVault — the on-chain receipt for a physical slab in custody (ERC-721).
CompOracle — pushes each card's value on chain from sales comps.
SlabLend — the USDC pool: supply, borrow against a slab, repay.
LiquidationAuction — the English auction that settles bad loans.

Every loan is one slab against USDC, isolated in its own position. Nothing is pooled at the collateral level and nothing is rehypothecated.

The vault

You ship a graded card (PSA, BGS, CGC) to the custodian. It is stored insured, and a receipt token is minted to your wallet. The receipt carries the card's grading cert and a cardKey that the oracle prices against.

Holding the receipt means holding the card. You can redeem it at any time it is not locked as collateral, and the custodian ships the physical slab back to you.

The receipt is the claim. Lock it to borrow, or redeem it for delivery. It is never in two places at once.

Pricing & comps

Cards do not have an on-chain price feed, so an authorized appraiser pushes each card's value from live comparable sales (PriceCharting, PSA auction prices). A global haircut discounts the raw comp to a conservative mark, and every mark carries a timestamp.

If a mark goes stale (older than the max age), the loan against it becomes liquidatable, because the protocol can no longer trust the price. Fresh, conservative marks are the trust anchor of the whole system.

Borrowing

Lock a slab to open a loan, then draw USDC up to the max LTV (50% of the haircut mark by default). The liquidation threshold is higher (65%): the gap is your buffer against interest and small price moves.

Borrow up to 50% of the marked value.
Repay any amount, any time. Interest stops accruing on what you repay.
Clear the debt to close the loan and unlock the slab.

Interest & supply

Lenders supply USDC to the pool and receive shares. Interest paid by borrowers accrues into the pool per second, so each share is worth more over time. Withdraw whenever there is idle liquidity (cash not currently lent out).

Suppliers take the credit risk of the book: if an auction recovers less than a loan's debt, the shortfall is borne pro-rata by suppliers. Conservative haircuts and LTVs exist to make that rare.

Liquidation auction

When a loan's debt exceeds the liquidation threshold, or its comp goes stale, anyone can call liquidate. The debt is frozen and the slab is sent to an English auction:

Bids are in USDC. Only slab holders may bid, so cards stay in the community.
Each bid must beat the last by at least 5%. A bid in the final 15 minutes extends the clock (anti-snipe).
On settle: the pool is repaid up to the debt, the liquidator earns the penalty, and any surplus returns to the borrower. The winner receives the slab.
No bids means the card goes to the treasury and the debt is written off.

Contracts

Live on Ethereum mainnet:

SlabLend 0x232CE11723296DD45BFF53fF72F1464e04C14a9B
SlabVault 0x791efb59F88653D04617db75cE76AE29BbB43613
CompOracle 0xa2cE3a2B6d9E4910c6Ca91D00182bcD2Bb3DfA47
LiquidationAuction 0x657011eC4139E2CD97580C5c60982E0A5d427907