# Exchange shards

Kalshi's numbered exchange shards: each market lives on one, an account holds cash per shard and an order debits its market's shard.

Kalshi runs its exchange as shards numbered `0` to `3`, and the simulator does the same. Every market lives on one shard, named by its `exchange_index`. An account holds cash per shard (`balance_breakdown`), and trades a market only on a shard where it's provisioned (`exchange_presence`). An order routes to its market's shard by the body's `exchange_index`, or by ticker when that's omitted or `-1`. Its fill debits that shard's cash.

The `shard2_world` scenario holds a market on shard 2 and a `member` funded there:

```bash
export RYSTIC_URL=$(rystic run kalshi-twin -d --port 0 --name shards --scenario shard2_world --json | jq -r .data.url)
curl -s "$RYSTIC_URL/trade-api/v2/markets" | jq -c '.markets[] | {ticker, exchange_index}'
# -> {"ticker":"KXBTCSHD-26-W","exchange_index":2}
curl -s "$RYSTIC_URL/trade-api/v2/portfolio/balance?exchange_index=2" | jq -c '{balance_dollars}'
# -> {"balance_dollars":"5000.0000"}
curl -s "$RYSTIC_URL/trade-api/v2/portfolio/balance" | jq -c '.balance_breakdown | map({exchange_index, balance})'
# -> [{"exchange_index":0,"balance":"5000.0000"},{"exchange_index":1,"balance":"0.0000"},{"exchange_index":2,"balance":"5000.0000"},{"exchange_index":3,"balance":"0.0000"}]
```

- **A balance seeded without `balance_breakdown` is a one-shard account on shard 0.** An order on a market on another shard returns `404 user_not_found`, as on the exchange.
- **A replayed or live-fed market keeps its real shard**, read from its market record. With no record (the metadata fetch turned off or unreachable, and no `meta/`) it sits on shard 0. `GET /trade-api/v2/markets/{ticker}` shows it, and `GET /trade-api/v2/portfolio/balance?exchange_index=2` shows that shard's cash.
- **Fund the shard in the seed.** This balance holds cash on shards 0 and 2 and provisions both:

```json
{"state_balance": {"member": {
  "balance": 1000000, "balance_dollars": "10000.0000",
  "portfolio_value": 0, "updated_ts": 1784989800,
  "balance_breakdown": [{"exchange_index": 0, "balance": "0.0000"},
                        {"exchange_index": 2, "balance": "10000.0000"}],
  "exchange_presence": [0, 2]
}}}
```

### One cash pool

Start the simulator with `KALSHI_REPLAY_SHARD=0`, and every market a tape or the live feed creates is placed on shard 0, whatever its record says. So a plain balance seed funds them all. Any other non-negative index works the same way, and a value that isn't one is ignored and logged. A market you seed yourself keeps the `exchange_index` you give it.

**Differs from Kalshi:** with `KALSHI_REPLAY_SHARD` set, routing, per-shard cash and transfers no longer reflect where the markets really live.

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Source: https://www.rystic.ai/docs/simulators/kalshi/features/exchange-shards · Markdown: https://www.rystic.ai/docs/simulators/kalshi/features/exchange-shards.md