🤝Itayose: Fair Price Discovery

The opening auction that sets a fair price for every new market

Itayose (板寄せ — the call-auction method used by Japanese exchanges) determines the opening price whenever a new order book starts trading. Instead of letting the first trade set an arbitrary price, all pre-open orders are matched simultaneously at a single fair price.

The three phases

Before opening (pre-open period)

• Starting 7 days before a new order book opens, users may place limit orders only, and only on one side (you can't quote both sides — a manipulation guard).

• The app displays the estimated opening APR based on the evolving pre-open book.

• 1 hour before opening, the book freezes — no placing, amending, or canceling.

During Itayose

The smart contract consolidates all overlapping bids and offers and computes the opening price to maximize executed volume, considering total lend amount, total borrow amount, and the imbalance between them. With no imbalance, the mid-price is taken; with an imbalance, the price moves toward the heavier side. If no orders overlap, the market simply opens without an opening price.

Fees are waived for all orders filled during Itayose — an incentive to participate in price discovery.

After opening

Orders executed by Itayose all fill at the single opening price. Unfilled orders remain on the book as normal limit orders when continuous trading begins.

Worked examples

Balanced book: lend orders total 100,000 USDC and borrow orders total 100,000 USDC in the overlapping range 98.10–98.40 → the opening price is the mid, 98.25, and everything fills.

Imbalanced book (more lenders): 180,000 USDC of lend orders vs 120,000 USDC of borrow orders overlap in 97.60–97.90 → the price settles toward the lend side at 97.70; all 120,000 of borrows fill, lend orders fill 120,000 by time priority, and the remaining 60,000 rest on the book at open.

No overlap: highest borrow price 95.80 < lowest lend price 96.00 → no matching; the market opens with all pre-orders resting.

Why it matters

• Fair access — everyone who participates gets the same opening price

• Liquidity from block one — new markets open with a populated book, not a void

• Manipulation resistance — single-side quoting, the freeze window, and volume-maximizing pricing make the open hard to game

Related

• Market Listing & Delisting — when Itayose runs

• Orderbook Rotation — the quarterly cycle it belongs to

• Fees — the Itayose fee waiver