Gemini Prediction Markets API

Trading (1.0.0)

Endpoint

Authenticated endpoints for placing and managing orders (currently only limit orders are supported)

Place order

POST

https://api.gemini.com

/v1/prediction-markets/order

Place a new prediction market limit order. Currently only limit orders are supported. Requires authentication and NewOrder permission.

Place order › Request Body

symbol

string · required

Contract instrument symbol

Example: GEMI-FEDJAN26-DN25

orderType

string · enum · required

Order type (currently only limit orders are supported)

Enum values:

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

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 (currently only limit orders are supported)

Enum values:

limit

quantity

string

Original order quantity

filledQuantity

string

Amount filled so far

remainingQuantity

string

Amount remaining to fill

price

string

Limit price

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 limit order. Currently only limit orders are supported. Requires authentication and NewOrder permission.

Place order › Request Body

symbol

string · required

Contract instrument symbol

Example: GEMI-FEDJAN26-DN25

orderType

string · enum · required

Order type (currently only limit orders are supported)

Enum values:

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

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 (currently only limit orders are supported)

Enum values:

limit

quantity

string

Original order quantity

filledQuantity

string

Amount filled so far

remainingQuantity

string

Amount remaining to fill

price

string

Limit price

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