Last Modified: July 25, 2017

Gemini operates three distinct order matching engines, one for each of our trading pairs—BTC/USD, ETH/USD, and ETH/BTC. Customers may submit orders to any of the three matching engines at any time. Our marketplace operates 24 hours a day, seven days a week (except for brief maintenance periods).

Customers may submit as many orders as they want of the types described below. Because Gemini is a full reserve exchange, we require that all trades be pre-funded (i.e., assets must be on deposit in your account before attempting to trade them). All open orders reduce customers’ available balance until the orders are fulfilled or canceled.

We currently offer two BTC/USD auctions per day, one at 4:00 p.m. Eastern Time and another at 7:00 p.m. Singapore Time and Hong Kong Time (20:00 JST), and one ETH/USD auction per day at 4:00 pm. Eastern Time.

Order Types

Our order matching engine currently supports six order types, as described below.

Continuous Trading

Specifies Price Trades Against Resting Orders Can Rest on Continuous Trading Order Book Can Trade in Auction
Market Yes
Limit Yes Yes Yes Yes
Immediate-or-Cancel (IOC) Yes Yes
Maker-or-Cancel (MOC) Yes Yes Yes
Auction-Only (AO) Market Yes
Auction-Only (AO) Limit Yes Yes
Continuous Trading

For each trading pair, we offer a continuous trading order book. This allows for continual interactions between market orders and limit orders. Limit orders interacting with the order book may additionally carry one of two options (see below).

Customers who wish to trade immediately may enter market orders to buy or sell. Because these orders do not specify a price constraint, they may be fulfilled at any price or a variety of prices by orders already resting on our limit order book (see below). For ease of use, market orders to buy must specify a total notional value to convert from one asset to another (e.g., buy $100 worth of bitcoin), from which appropriate trading fees are first deducted. Market orders to sell must specify a total quantity of asset to sell (e.g., sell 5 BTC for USD); appropriate trading fees are deducted from the proceeds. For a more detailed discussion of fees, please see Trading Fees & Rebates.

As with most other marketplaces, customers may also place limit orders to buy or sell. These orders might not trade immediately if no other customer is willing to trade at the specified limit price (or better). Any untraded quantity rests on our order book until fulfilled by incoming eligible orders. Thus, a limit order might not immediately be fulfilled; trades depend on interactions with other marketplace participants. Customers may attempt to cancel orders while they rest on the order book. The quantity and limit price are specified separately from fees. (Gemini does not currently allow limit orders to be “replaced” or “amended;” customers must enter an entirely new order to specify a different limit price or quantity.)

Our marketplace also allows limit orders to be entered with one of two order options: immediate-or-cancel (“IOC”) or maker-or-cancel (“MOC”). IOC orders are common on other marketplaces. This option specifies that a limit order should not be allowed to rest on the order book; instead, any quantity not executed immediately is canceled. MOC specifies the opposite: if the limit order would trade immediately against an eligible resting order, it is instead canceled. MOC orders only trade after first resting on the order book. In summary, all trades from IOC orders are liquidity-taking, and all trades from MOC orders are liquidity-making.

Priority of Orders Book

Limit orders resting on our book are sorted by price-time priority. That is, if an incoming market or limit order could be fulfilled by multiple resting limit orders, eligible orders at the most favorable price are considered first (i.e., lowest resting sell orders for an incoming buy or highest resting buy orders for an incoming sell). If multiple limit orders are resting at the same price, those which were placed earlier are considered before those which were placed more recently. Partially filled resting limit orders keep their priority until canceled.


In addition to the continuous trading order book, the BTC/USD order matching engine conducts two Auctions (or “crosses”) every day, one at 4:00 p.m. Eastern Time (20:00 UTC during EDT and 21:00 UTC during EST) and one at 7:00 p.m. Singapore Time and Hong Kong Time (20:00 JST, 11:00 UTC); and the ETH/USD order matching engine conducts one Auction every day at 4:00 p.m. Eastern Time. This provides an opportunity for both buyers and sellers to trade in an instant of elevated liquidity and price discovery. All active orders (including resting limit and MOC orders) may interact with the Auction and influence the final auction price, which is determined by finding the price at which the greatest aggregate buy demand and sell demand are fulfilled. All participating, eligible orders are fulfilled at the final auction price. (We use a mechanism similar to the New York Stock Exchange’s Arca marketplace, Nasdaq, Bats, and other large stock exchanges throughout Europe and Asia, which is sometimes called Walrasian equilibrium.)

ET Auction SGT/HKT Auction
AO Orders Accepted 8:00 a.m. 12:00 13:00 11:00 a.m. 12:00 03:00
Indicative Prices 3:50 p.m. 19:50 20:50 6:50 p.m. 19:50 10:50
AO Orders Locked In 3:59 p.m. 19:59 20:59 6:59 p.m. 19:59 10:59
Auction 4:00 p.m. 20:00 21:00 7:00 p.m. 20:00 11:00

Customers may enter both market orders and limit orders as auction-only (AO), indicating that they will not take part in continuous trading (as described above) but instead only become eligible to trade at the time of the Auction. Customers may submit as many auction-only orders as they want for a particular Auction, provided all orders are pre-funded. If not all eligible orders can be fulfilled during the Auction (which can occur when demand on one side of the market outweighs demand on the other), they will be given priority based on receipt time. If an auction-only limit order cannot be satisfied by the final auction price, it will be canceled back to the customer after the completion of the Auction. Each Auction begins accepting auction-only orders ten hours before the Auction time. Auction-only orders may be canceled up until one minute before the Auction; after that time, they’re locked in to the Auction.

The final auction price of each Auction is determined by finding the price at which the greatest aggregate buy demand and sell demand from all eligible orders are fulfilled; all continuous trading book orders and auction-only orders are considered. (In the event of a tie between multiple prices, the midrange is used.) Beginning ten minutes before the Auction, indications of the upcoming auction price are broadcast via both our market data API (see below) and the website UI. (In order to calculate these indications, we simulate the auction process for the order books at that time.) These indicative auction prices are updated every 60 seconds leading into the Auction, and every 15 seconds during the last minute. In general, these indications should converge on the final auction price and should also provide guidance for prices on the continuous trading order books.1 If the matching engine cannot converge on an effective2 final auction price, the Auction will be canceled, all auction-only orders will be canceled back, and all continuous trading book orders will be unaffected.

Check out our Auction Data page to see the results of Gemini’s previous auctions.

Market Data

All trades on our marketplace are reported both to the customer and to the public via our market data API. The summed quantity of limit orders (only standard and MOC) resting at each price level throughout our three order books is also publicly available via our market data API. Additionally, the value of each digital asset is determined by the most recent trade (sometimes called last price) executed by the relevant matching engine; this convention is called “marking to market.” All Account Balances on Gemini are marked to market.

1 Gemini makes no guarantee that these prices will converge throughout the process nor that the continuous trading prices will converge. This outcome depends entirely on the efficiency of market makers and other participants who have no affiliation with Gemini Trust Company, LLC.
2 The matching engine requires that the final auction price differ from the midpoint of the continuous trading order book at the time of the Auction by no more than 5 %.