Gemini Prediction Markets API

Trading (1.0.0)

Endpoint

Authenticated endpoints for placing and managing orders

Place order

POST

https://api.gemini.com

/v1/prediction-markets/order

Place a new prediction market order. Supports limit and stop-limit order types. Requires authentication and NewOrder permission.

Stop-Limit Orders

A stop-limit order is an order type that allows for order placement when a price reaches a specified level. Stop-limit orders take in both a price and a stopPrice as parameters. The stopPrice is the price that triggers the order to be placed on the continuous live order book at the price. For buy orders, the stopPrice must be greater than or equal to the last trade price and less than or equal to the price; for sell orders, the stopPrice must be less than or equal to the last trade price and greater than or equal to the price. Both price and stopPrice must be in the 0-1 range.

Place order › Request Body

symbol

string · required

Contract instrument symbol

Example: GEMI-FEDJAN26-DN25

orderType

string · enum · required

Order type. stop-limit orders require a stopPrice that triggers a limit order at price when the market reaches the trigger.

Enum values:

limit

stop-limit

side

string · enum · required

Enum values:

buy

sell

quantity

string · required

Number of contracts

Example: 100

price

string · required

Limit price (0-1 range)

Example: 0.65

outcome

string · enum · required

The outcome being traded (Yes or No)

Enum values:

yes

stopPrice

string

The price to trigger a stop-limit order (0-1 range). Only available for stop-limit orders. See Stop-Limit Orders above for stopPrice/price constraints.

Example: 0.60

timeInForce

string · enum

Order execution behavior:

good-til-cancel - Order remains active until filled or cancelled (default)
immediate-or-cancel - Fill immediately or cancel remaining
fill-or-kill - Fill entire order immediately or cancel
maker-or-cancel - Only add liquidity to the order book; if any part would fill immediately, the entire order is cancelled. Also known as "post-only".

Enum values:

good-til-cancel

immediate-or-cancel

fill-or-kill

maker-or-cancel

Default: good-til-cancel

Place order › Responses

Order created successfully

orderId

integer · int64

hashOrderId

string | null

clientOrderId

string | null

globalOrderId

string | null

status

string · enum

Enum values:

open

filled

cancelled

symbol

string

side

string · enum

Enum values:

buy

sell

outcome

string · enum

The outcome being traded (Yes or No)

Enum values:

yes

orderType

string · enum

Order type. stop-limit orders require a stopPrice that triggers a limit order at price when the market reaches the trigger.

Enum values:

limit

stop-limit

quantity

string

Original order quantity

filledQuantity

string

Amount filled so far

remainingQuantity

string

Amount remaining to fill

price

string

Limit price

stopPrice

string | null

Stop trigger price (populated for stop-limit orders)

avgExecutionPrice

string | null

Average price of fills

createdAt

string · date-time

updatedAt

string · date-time

cancelledAt

string | null · date-time

object

POST/v1/prediction-markets/order

curl --request POST \
  --url https://api.gemini.com/v1/prediction-markets/order \
  --header 'Content-Type: application/json' \
  --data '
{
  "symbol": "GEMI-FEDJAN26-DN25",
  "orderType": "limit",
  "side": "buy",
  "quantity": "100",
  "price": "0.65",
  "outcome": "yes",
  "timeInForce": "good-til-cancel"
}
'

shell

Example Request Body

{
  "symbol": "GEMI-FEDJAN26-DN25",
  "orderType": "limit",
  "side": "buy",
  "quantity": "100",
  "price": "0.65",
  "outcome": "yes",
  "timeInForce": "good-til-cancel"
}

json

Place a limit order to buy 100 YES contracts at 0.65

application/json

Example Responses

{
  "orderId": 12345678901,
  "status": "open",
  "symbol": "GEMI-FEDJAN26-DN25",
  "side": "buy",
  "outcome": "yes",
  "orderType": "limit",
  "quantity": "100",
  "filledQuantity": "0",
  "remainingQuantity": "100",
  "price": "0.65",
  "avgExecutionPrice": null,
  "createdAt": "2025-12-15T10:30:00.000Z",
  "updatedAt": "2025-12-15T10:30:00.000Z",
  "cancelledAt": null,
  "contractMetadata": {
    "contractId": "contract_123",
    "contractName": "FEDJAN26-DN25",
    "contractTicker": "FEDJAN26-DN25",
    "eventTicker": "FEDJAN26",
    "eventName": "Will Fed Funds Rate drop at least 0.25% at January 2026 meeting?",
    "category": "economics",
    "contractStatus": "active",
    "imageUrl": "https://example.com/fed.png",
    "expiryDate": "2026-01-31T23:59:59.000Z",
    "resolvedAt": null,
    "description": "Resolves YES if Federal Reserve lowers the target rate by 0.25% or more at the January 2026 FOMC meeting"
  }
}

json

application/json

Cancel order

POST

https://api.gemini.com

/v1/prediction-markets/order/cancel

Cancel an existing prediction market order. Requires authentication and CancelOrder permission.

Cancel order › Request Body

orderId

integer · int64 · required

The order ID to cancel

Example: 12345678

Cancel order › Responses

Order cancelled successfully

result

string

message

string

POST/v1/prediction-markets/order/cancel

curl --request POST \
  --url https://api.gemini.com/v1/prediction-markets/order/cancel \
  --header 'Content-Type: application/json' \
  --data '
{
  "orderId": 12345678
}
'

shell

Example Request Body

{
  "orderId": 12345678
}

json

Example Responses

{
  "result": "ok",
  "message": "Order 12345678 cancelled successfully"
}

json

application/json

Markets Positions

Place order

POST

https://api.gemini.com

/v1/prediction-markets/order

Place a new prediction market order. Supports limit and stop-limit order types. Requires authentication and NewOrder permission.

Stop-Limit Orders

Place order › Request Body

symbol

string · required

Contract instrument symbol

Example: GEMI-FEDJAN26-DN25

orderType

string · enum · required

Order type. stop-limit orders require a stopPrice that triggers a limit order at price when the market reaches the trigger.

Enum values:

limit

stop-limit

side

string · enum · required

Enum values:

buy

sell

quantity

string · required

Number of contracts

Example: 100

price

string · required

Limit price (0-1 range)

Example: 0.65

outcome

string · enum · required

The outcome being traded (Yes or No)

Enum values:

yes

stopPrice

string

The price to trigger a stop-limit order (0-1 range). Only available for stop-limit orders. See Stop-Limit Orders above for stopPrice/price constraints.

Example: 0.60

timeInForce

string · enum

Order execution behavior:

good-til-cancel - Order remains active until filled or cancelled (default)
immediate-or-cancel - Fill immediately or cancel remaining
fill-or-kill - Fill entire order immediately or cancel
maker-or-cancel - Only add liquidity to the order book; if any part would fill immediately, the entire order is cancelled. Also known as "post-only".

Enum values:

good-til-cancel

immediate-or-cancel

fill-or-kill

maker-or-cancel

Default: good-til-cancel

Place order › Responses

Order created successfully

orderId

integer · int64

hashOrderId

string | null

clientOrderId

string | null

globalOrderId

string | null

status

string · enum

Enum values:

open

filled

cancelled

symbol

string

side

string · enum

Enum values:

buy

sell

outcome

string · enum

The outcome being traded (Yes or No)

Enum values:

yes

orderType

string · enum

Order type. stop-limit orders require a stopPrice that triggers a limit order at price when the market reaches the trigger.

Enum values:

limit

stop-limit

quantity

string

Original order quantity

filledQuantity

string

Amount filled so far

remainingQuantity

string

Amount remaining to fill

price

string

Limit price

stopPrice

string | null

Stop trigger price (populated for stop-limit orders)

avgExecutionPrice

string | null

Average price of fills

createdAt

string · date-time

updatedAt

string · date-time

cancelledAt

string | null · date-time

object

curl --request POST \ --url https://api.gemini.com/v1/prediction-markets/order \ --header 'Content-Type: application/json' \ --data ' { "symbol": "GEMI-FEDJAN26-DN25", "orderType": "limit", "side": "buy", "quantity": "100", "price": "0.65", "outcome": "yes", "timeInForce": "good-til-cancel" } '

{ "orderId": 12345678901, "status": "open", "symbol": "GEMI-FEDJAN26-DN25", "side": "buy", "outcome": "yes", "orderType": "limit", "quantity": "100", "filledQuantity": "0", "remainingQuantity": "100", "price": "0.65", "avgExecutionPrice": null, "createdAt": "2025-12-15T10:30:00.000Z", "updatedAt": "2025-12-15T10:30:00.000Z", "cancelledAt": null, "contractMetadata": { "contractId": "contract_123", "contractName": "FEDJAN26-DN25", "contractTicker": "FEDJAN26-DN25", "eventTicker": "FEDJAN26", "eventName": "Will Fed Funds Rate drop at least 0.25% at January 2026 meeting?", "category": "economics", "contractStatus": "active", "imageUrl": "https://example.com/fed.png", "expiryDate": "2026-01-31T23:59:59.000Z", "resolvedAt": null, "description": "Resolves YES if Federal Reserve lowers the target rate by 0.25% or more at the January 2026 FOMC meeting" } }

Cancel order

POST

https://api.gemini.com

/v1/prediction-markets/order/cancel

Cancel an existing prediction market order. Requires authentication and CancelOrder permission.

Cancel order › Request Body

orderId

integer · int64 · required

The order ID to cancel

Example: 12345678

Cancel order › Responses

Order cancelled successfully

result

string

message

string