Stream Prediction Positions

This endpoint is in closed beta. It is available only to accounts enrolled in the beta, and only on staging (https://api.tradearies.dev). Request and response shapes may change before general availability.

Booked values only. The stream carries what fills have booked: quantity, cost, average price, and realized P&L. It has no mark price and no unrealized P&L, so it sends an update when a fill changes a position and not on every price tick. Compute unrealized P&L on the client from the live price stream; see Unrealized P&L.

Request

GET /v1/predictions/positions/stream?accountId=ACCOUNT-0001

Parameter	Description
`accountId`	Required. The account whose positions to stream.

Authenticate the same way as Stream Prediction Orders. The stream carries only the authenticated user’s own positions: an account you have no positions on streams an empty snapshot and nothing after it. The first line of the response is retry: 2000, which tells an EventSource to wait two seconds before it reconnects.

Events

Event	When	Payload
`snapshot`	First, once	`accountId` and `positions`: the account’s open positions
`position`	Each time one of the account’s positions changes	One position
`resync`	When the stream is about to end	`reason`: `slow_client` or `shutdown`

A : ping comment is sent every 15 seconds to keep idle connections open.

snapshot

{
  "accountId": "ACCOUNT-0001",
  "positions": [
    {
      "accountId": "ACCOUNT-0001",
      "symbol": "HORC_1126_Republican",
      "outcome": "YES",
      "qty": "10",
      "cost": "5.40",
      "avgPx": "0.54",
      "realizedPnl": "0",
      "version": 3,
      "createdAt": "2026-10-08T14:02:15.103Z",
      "updatedAt": "2026-10-08T14:02:15.103Z"
    }
  ]
}

positions holds only open positions, those with a non-zero qty. A position that is flat is not in the snapshot.

position

{
  "accountId": "ACCOUNT-0001",
  "symbol": "HORC_1126_Republican",
  "outcome": "YES",
  "qty": "15",
  "cost": "8.15",
  "avgPx": "0.5433",
  "realizedPnl": "0",
  "version": 4,
  "createdAt": "2026-10-08T14:02:15.103Z",
  "updatedAt": "2026-10-08T14:20:41.870Z"
}

Each position is the whole row as it stands after the change, not a delta. Replace the row you hold for that symbol when the event’s version is higher than the one you have. When qty is "0" the position has closed: remove the row.

{
  "accountId": "ACCOUNT-0001",
  "symbol": "HORC_1126_Republican",
  "outcome": "",
  "qty": "0",
  "cost": "0",
  "avgPx": "0",
  "realizedPnl": "1.85",
  "version": 5,
  "createdAt": "2026-10-08T14:02:15.103Z",
  "updatedAt": "2026-10-08T15:47:09.226Z"
}

resync

{ "reason": "slow_client" }

The stream ends right after a resync. Reconnect, and the new snapshot brings your view up to date. slow_client means you stopped reading events fast enough to keep up; shutdown means the server is restarting.

Position fields

Decimals are strings: "0.54", not 0.54.

Field	Description
`accountId`	The account holding the position.
`symbol`	The contract. A position is keyed by `symbol`: an account has at most one position per contract.
`outcome`	`YES` or `NO`, the outcome held. Empty (`""`) when the position is flat.
`qty`	Contracts held. `"0"` means the position has closed.
`cost`	The cost booked for the contracts held.
`avgPx`	The average price of the contracts held.
`realizedPnl`	Profit and loss realized so far.
`version`	An `int64` that rises with every change to the position. It is the only ordering; see Ordering.
`createdAt`	When the position was first opened.
`updatedAt`	When the position last changed.

ForecastEx takes buy orders only, so a position holds one outcome at a time. Buying the other outcome of a contract you hold does not open a second position: it nets against the one you have.

Unrealized P&L

Positions carry no mark price and no unrealized P&L. Take the last price for the held outcome from the live price stream, where each contract’s snapshot has a yes.last and a no.last, and compute:

unrealized P&L = (last − avgPx) × qty

Use yes.last when outcome is YES and no.last when it is NO. Do the arithmetic with a decimal type. If that outcome has not traded, last is null: show no unrealized P&L rather than zero.

Ordering

Every position carries a version that rises with each change. Keep the highest version you have seen for each symbol, and ignore a position at or below it. The stream already drops older versions, but applying this rule makes your client correct across reconnects too.
Never order by time. createdAt and updatedAt are for display. Only version says which row is newer.
snapshot comes first. Every position after it is newer than the snapshot’s copy of that position.
Changes to one position arrive in the order they happened. Changes to different positions may interleave.

Reconnecting

Events have no IDs and are not replayed, and there is no Last-Event-ID resume. Every connection starts with a fresh snapshot, so after a disconnect or a resync, reconnect and replace all your positions with the new snapshot. A change that happened while you were disconnected is reflected in it, and a position that closed while you were away is no longer in it. EventSource reconnects on its own after the retry: 2000 delay. A client that reads the stream with fetch has to reconnect itself, as the example below does.

Examples

cURL

curl -N "https://api.tradearies.dev/v1/predictions/positions/stream?accountId=ACCOUNT-0001" \
  -H "Authorization: Bearer $ACCESS_TOKEN"

A browser’s EventSource cannot send an Authorization header, so read the stream with fetch:

JavaScript

const positions = new Map(); // symbol -> position

function apply(position) {
  if (position.qty === "0") {
    positions.delete(position.symbol);
    return;
  }
  const held = positions.get(position.symbol);
  if (!held || position.version > held.version) {
    positions.set(position.symbol, position);
  }
}

async function streamPositions(accountId, accessToken) {
  const res = await fetch(
    `https://api.tradearies.dev/v1/predictions/positions/stream?accountId=${encodeURIComponent(accountId)}`,
    { headers: { Authorization: `Bearer ${accessToken}` } }
  );
  if (!res.ok) throw new Error(`stream refused: ${res.status}`);

  const reader = res.body.pipeThrough(new TextDecoderStream()).getReader();
  let buffer = "";
  for (;;) {
    const { value, done } = await reader.read();
    if (done) return; // the stream ended: reconnect
    buffer += value;
    let end;
    while ((end = buffer.indexOf("\n\n")) >= 0) {
      const frame = buffer.slice(0, end);
      buffer = buffer.slice(end + 2);
      const event = frame.match(/^event: (.*)$/m)?.[1];
      const data = frame.match(/^data: (.*)$/m)?.[1];
      if (event === "snapshot") {
        positions.clear();
        JSON.parse(data).positions.forEach(apply);
      } else if (event === "position") {
        apply(JSON.parse(data));
      }
    }
  }
}

async function keepStreaming(accountId, accessToken) {
  for (;;) {
    try {
      await streamPositions(accountId, accessToken);
    } catch (err) {
      console.error(err);
    }
    await new Promise((resolve) => setTimeout(resolve, 2000));
  }
}

To show unrealized P&L, keep each contract’s latest yes.last and no.last from the live price stream and combine them with the held row:

JavaScript

function unrealizedPnl(position, quote) {
  const last = position.outcome === "YES" ? quote.yes?.last : quote.no?.last;
  if (last == null) return null; // the held outcome has not traded
  return (Number(last) - Number(position.avgPx)) * Number(position.qty);
}

Number keeps the example short. In production, use a decimal library for money.

Working with the stream

Prices, quantities, and P&L are decimal strings. Parse them with a decimal type.
Do not put the stream behind a buffering proxy. Events must reach you as they are sent.

Errors

Errors are returned before the stream opens, in the usual error envelope:

Status	`code`	When
`400`	`INVALID_STREAM_REQUEST`	`accountId` is missing.
`401`	—	Missing or invalid credentials.
`500`	`POSITION_STREAM_FAILED`	Unexpected server error.
`503`	`POSITION_STREAM_UNAVAILABLE`	The server is restarting or busy; retry shortly.

Historical Data

Reference Data

Live Data

Orders

Stream Prediction Positions

Request

Events

snapshot

position

resync

Position fields

Unrealized P&L

Ordering

Reconnecting

Examples

Working with the stream

Errors

​Request

​Events

​snapshot

​position

​resync

​Position fields

​Unrealized P&L

​Ordering

​Reconnecting

​Examples

​Working with the stream

​Errors

Request

Events

snapshot

position

resync

Position fields

Unrealized P&L

Ordering

Reconnecting

Examples

Working with the stream

Errors