> ## Documentation Index > Fetch the complete documentation index at: https://developers.circle.com/llms.txt > Use this file to discover all available pages before exploring further. # Fund trades > Executes funding for trades using Permit2 signatures. This endpoint relays the signed permit data to complete the funding operation for trades. When `fundingMode` is `delegate`, the request must include the trader's delegate-funding authorization in `permit2`/`signature` along with the funder's permit in `funderPermit2`/`funderSignature`. The funder delivers the tokens on the trader's behalf; no tokens transfer from the trader. ## OpenAPI ````yaml openapi/stablefx.yaml post /v1/exchange/stablefx/fund openapi: 3.1.0 info: title: StableFX API description: > The StableFX API provides endpoints for trading stablecoins. ## Authentication All API requests require authentication using an API key. ## Base URL The base URL for all API endpoints is: `https://api.circle.com/v1/exchange/stablefx` version: 1.0.0 servers: - url: https://api.circle.com description: StableFX API server security: - BearerAuth: [] tags: - name: Quotes description: Endpoints for creating and managing quotes - name: Trades description: Endpoints for creating and managing trades - name: Signatures description: Endpoints for retrieving presign typed data and registering signatures - name: Fees description: Endpoints for retrieving fees - name: Funding description: Endpoints for funding trades - name: Webhook Subscriptions description: Manage subscriptions to notifications - name: Settlement Advance description: Request, track, and repay settlement advances. paths: /v1/exchange/stablefx/fund: post: tags: - Funding summary: Fund trades description: > Executes funding for trades using Permit2 signatures. This endpoint relays the signed permit data to complete the funding operation for trades. When `fundingMode` is `delegate`, the request must include the trader's delegate-funding authorization in `permit2`/`signature` along with the funder's permit in `funderPermit2`/`funderSignature`. The funder delivers the tokens on the trader's behalf; no tokens transfer from the trader. operationId: fundTrade requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/Fund' responses: '200': description: Funding completed successfully '400': description: Bad request - validation error security: - BearerAuth: [] components: schemas: Fund: type: object description: Request body for funding operations required: - type - signature - permit2 properties: type: $ref: '#/components/schemas/Type' signature: type: string description: The trader's Permit2 signature over `permit2` example: 0x1234567890abcdef... fundingMode: allOf: - $ref: '#/components/schemas/FundingMode' - type: - string - 'null' description: The funding mode for the operation (optional) permit2: oneOf: - $ref: '#/components/schemas/Permit2SingleFundingMessage' - $ref: '#/components/schemas/Permit2BatchFundingMessage' - $ref: '#/components/schemas/DelegateFundingPermit2' discriminator: propertyName: witness mapping: SingleTradeWitness: $ref: '#/components/schemas/Permit2SingleFundingMessage' BatchTradeWitness: $ref: '#/components/schemas/Permit2BatchFundingMessage' DelegateFundingAuthorization: $ref: '#/components/schemas/DelegateFundingPermit2' description: >- The Permit2 message object signed by the trader. Single or batch funding message for `gross`/`net` funding modes; delegate-funding authorization (with `permitted.amount` of 0) when `fundingMode` is `delegate`. funderPermit2: allOf: - $ref: '#/components/schemas/DelegateFundingFunderPermit2' description: >- The Permit2 message object signed by the funder, carrying the actual delivery amount. Required when `fundingMode` is `delegate`. funderSignature: type: string description: >- The funder's Permit2 signature over `funderPermit2`. Required when `fundingMode` is `delegate`. example: 0xabcdef1234567890... Type: type: string description: The type of trader. enum: - maker - taker FundingMode: type: string description: > The funding mode for funding requests. - `gross`: the trader delivers the full amount for each trade. - `net`: the maker delivers the net difference across trades. Supported for maker funding requests only. - `delegate`: a funder wallet delivers tokens on the trader's behalf. The trader signs a zero-amount Permit2 authorization and the funder signs the Permit2 transfer carrying the delivery amount. enum: - gross - net - delegate default: gross Permit2SingleFundingMessage: type: object description: The message data for Permit2 signature required: - permitted - spender - nonce - deadline - witness properties: permitted: $ref: '#/components/schemas/TokenPermissions' spender: type: string description: The spender contract address example: '0xffd21ca8F0876DaFAD7de09404E0c1f868bbf1AE' nonce: type: string description: The nonce for the permit, as a string representation of a uint256 example: '42' deadline: type: string description: >- The deadline timestamp for the permit, as a string representation of a uint256 example: '1735689600' witness: $ref: '#/components/schemas/SingleTradeWitness' Permit2BatchFundingMessage: type: object description: The message data for Permit2 batch signature required: - permitted - spender - nonce - deadline - witness properties: permitted: type: array description: Array of token permissions items: $ref: '#/components/schemas/TokenPermissions' example: - token: 0xTOKEN1 amount: '1000' - token: 0xTOKEN2 amount: '2000' spender: type: string description: The spender contract address example: '0xffd21ca8F0876DaFAD7de09404E0c1f868bbf1AE' nonce: type: string description: The nonce for the permit, as a string representation of a uint256 example: '42' deadline: type: string description: >- The deadline timestamp for the permit, as a string representation of a uint256 example: '1735689600' witness: $ref: '#/components/schemas/BatchTradeWitness' DelegateFundingPermit2: type: object description: >- Permit2 PermitWitnessTransferFrom payload with DelegateFundingAuthorization witness. The `permitted.amount` is always 0 -- Permit2 is used as an authorization carrier, no tokens transfer from the trader. required: - permitted - spender - nonce - deadline - witness properties: permitted: $ref: '#/components/schemas/TokenPermissions' spender: type: string description: FxEscrow contract address. example: 0xFxEscrow000000000000000000000000000000000 nonce: type: string description: Permit2 nonce, as a string representation of a uint256. example: '1234567890' deadline: type: string description: >- Permit2 deadline (unix timestamp), as a string representation of a uint256. example: '1782556800' witness: $ref: '#/components/schemas/DelegateFundingAuthorization' DelegateFundingFunderPermit2: type: object description: >- Permit2 PermitWitnessTransferFrom payload signed by the funder when delivering tokens on a trader's behalf. Unlike the trader's authorization payload, this permit carries the actual delivery amount in `permitted.amount`. The DelegateFundingWitness binds the funder's signature to a specific trade and recipient, and must agree with the trader's DelegateFundingAuthorization. required: - permitted - spender - nonce - deadline - witness properties: permitted: $ref: '#/components/schemas/TokenPermissions' spender: type: string description: FxEscrow contract address. example: 0xFxEscrow000000000000000000000000000000000 nonce: type: string description: Permit2 nonce, as a string representation of a uint256. example: '1234567890' deadline: type: string description: >- Permit2 deadline (unix timestamp), as a string representation of a uint256. example: '1782556800' witness: $ref: '#/components/schemas/DelegateFundingWitness' TokenPermissions: type: object description: Token permissions for Permit2 required: - token - amount properties: token: type: string description: The token contract address example: 0xTOKEN amount: type: string description: >- The amount of tokens permitted, as a string representation of a uint256. example: '1000' SingleTradeWitness: type: object description: Single trade witness data required: - id properties: id: type: string description: The trade ID example: '10' BatchTradeWitness: type: object description: Batch trade witness data with multiple IDs required: - ids properties: ids: type: array description: Array of trade IDs items: type: string example: - '10' - '11' - '12' DelegateFundingAuthorization: type: object description: >- DelegateFundingAuthorization witness binding the Permit2 authorization to a specific trade, funder, recipient, token, and amount. required: - id - funder - recipient - token - amount properties: id: type: string description: On-chain trade id (uint256). example: '987654321' funder: type: string description: >- Address of the funder wallet (Circle-controlled) authorized to deliver tokens on the trader's behalf. example: 0xLLCFunderPW...address recipient: type: string description: Address that receives the delivered tokens. example: 0xLLCEscrowPW...address token: type: string description: ERC-20 contract address of the token to be delivered. example: 0xMXNB...address amount: type: string description: >- Amount to be delivered by the funder, in token units (uint256, no decimals). Tokens use 6 decimal places, so 5000.00 MXNB is represented as "5000000000". example: '5000000000' DelegateFundingWitness: type: object description: >- DelegateFundingWitness signed by the funder when delivering tokens on a trader's behalf. Both the trader (via DelegateFundingAuthorization) and the funder independently commit to the same recipient, and the contract verifies agreement on-chain. The funder address is not part of the witness because Permit2 verifies the signer identity via the `owner` parameter. required: - id - recipient properties: id: type: string description: On-chain trade id (uint256). example: '987654321' recipient: type: string description: >- Address that receives the delivered tokens. Must match the recipient in the trader's DelegateFundingAuthorization. example: '0xabcdef1234567890abcdef1234567890abcdef12' securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: PREFIX:ID:SECRET description: >- Circle's API Keys are formatted in the following structure "PREFIX:ID:SECRET". All three parts are requred to make a successful request. ````