> ## Documentation Index > Fetch the complete documentation index at: https://docs.kalshi.com/llms.txt > Use this file to discover all available pages before exploring further. # Exchange Sharding > Exchange sharding in the Predictions API ## Overview Kalshi splits trading across multiple matching engines to scale capacity. Exchange instances correspond to specific categories (e.g. "crypto" or "combos"). Kalshi plans to add shards incrementally to maintain a healthy balance of traffic. ## Balance Management Kalshi's collateralization checks run within the matching engine. Programmatic traders normally need to fund the relevant exchange shard before placing an order. FCM members can instead enable [automatic collateral transfers on eligible FIX sessions](/fix/authentication.md#optional-fields). **Funding Overview** * Account transfers can be made through the [Intra Account Transfer API](/api-reference/portfolio/intra-account-transfer.md). * Manual transfers are also available through the [Kalshi UI](https://kalshi.com/account/exchange-indexes). * [Get Balance](/api-reference/portfolio/get-balance.md) provides a breakdown of account balances across exchange indexes. **Automatic Order Transfers on the App and Web** Since the exchange sharding rollout, orders placed through the Kalshi App and Web automatically transfer capital between exchange shards as needed to fund the order. Market makers can disable this feature on the [Exchange Indexes settings page](https://kalshi.com/account/exchange-indexes). **Subaccounts Overview** * To fund a subaccount on a new exchange instance, first transfer user-level funds to the desired exchange instance. * Next, use [Create Subaccount](/api-reference/portfolio/create-subaccount.md) with the `exchange_index` parameter to provision the subaccount on the new instance. * Then, use [Transfer Between Subaccounts](/api-reference/portfolio/transfer-between-subaccounts.md) with the `exchange_index` parameter to transfer funds from the primary account to the subaccount on that instance. * [Get All Subaccount Balances](/api-reference/portfolio/get-all-subaccount-balances.md) provides a breakdown of subaccount balances for each `(exchange_index, subaccount)` pair. **Auto-Rebalancing** * Users may opt in to automatic rebalancing between exchange shards. * The customer supplies a target balance allocation as a percentage of their balance across exchange shards. For example, `{Default: 80, Combos: 20}`. * Every 10 seconds, Kalshi computes the customer's balance on each exchange shard as its account balance minus the value of its resting orders. * If the balance has drifted from the target allocation, Kalshi executes an intra-exchange account transfer on the customer's behalf to restore the target allocation. * Target balance allocations can be configured through the [REST API](/api-reference/portfolio/set-target-balance-allocation.md) and the clearing portal. ## Order routing ### Market Data * The `exchange_index` field is provided on [`GET /markets`](/api-reference/market/get-markets), [`GET /events`](/api-reference/events/get-events), and via the [market and event lifecycle WebSocket streams](/websockets/market-and-event-lifecycle.md) for newly created events and markets. * Market ticker formats are unaffected by exchange sharding. The `exchange_index` field is the authoritative source of truth. > [!WARNING] > > Auto-routing requires the market ticker: provide `market_ticker` for API2 or `Symbol<55>` for FIX. An order ID alone cannot identify the exchange shard. ### API2 The `exchange_index` query parameter is available on a per-endpoint basis. * If `exchange_index >= 0`, routes directly to the target exchange. * If `exchange_index` is `-1`, auto-routes using the required `market_ticker`. * If `exchange_index` is omitted and `market_ticker` is provided, auto-routes using `market_ticker`. * Otherwise, defaults to exchange index `0`. ### FIX [`ExDestination<100>`](/fix/order-entry) is available on a per-message basis for event-contract sessions. * If `ExDestination<100> >= 0`, routes directly to the target exchange. * If `ExDestination<100>` is `-1`, auto-routes using the required market ticker in `Symbol<55>`. * If `ExDestination<100>` is omitted and `Symbol<55>` is provided, auto-routes using `Symbol<55>`. Sessions with `UseCapReservation<21032>` or [automatic collateral transfers (`AutoTransfer<21035>`)](/fix/authentication#optional-fields) enabled must omit `ExDestination<100>` or use `-1` for new orders and replacements. Margined FIX sessions always route to exchange index `0`. ## Series Shard Assignments The following assignments determine the shard where new events are created. Shard 0 is the catch-all for all categories and tags not listed below. | Shard index | Category | Tags | Series list | | - | - | - | - | | 0 | *All other categories* | *All other tags* | — | | 1 | Exotics (Combos) | — | [`GET /series?category=Exotics`](https://api.elections.kalshi.com/trade-api/v2/series?category=Exotics) | | 2 | Crypto | — | [`GET /series?category=Crypto`](https://api.elections.kalshi.com/trade-api/v2/series?category=Crypto) | | 2 | Commodities | — | [`GET /series?category=Commodities`](https://api.elections.kalshi.com/trade-api/v2/series?category=Commodities) | | 3 | Sports | Tennis, Baseball, Basketball | [`GET /series?category=Sports&tags=Tennis,Baseball,Basketball`](https://api.elections.kalshi.com/trade-api/v2/series?category=Sports\&tags=Tennis%2CBaseball%2CBasketball) | ## FAQ * All child markets of an event will live on the same exchange instance. * There is currently no plan to migrate any live market to a new exchange instance. * Single REST order writes that explicitly target a nonzero shard are rate-limited against that shard's Write budget. Auto-routed single REST order writes are billed to the unscoped Write bucket and every nonzero shard's Write bucket. REST batch writes and explicit shard 0 writes use only the unscoped Write budget. See [Rate Limits and Tiers](/getting_started/rate_limits.md#sharded-exchanges-have-per-shard-write-budgets). * Providing `ExDestination` / `exchange_index` is unnecessary for all RFQ operations, including FIX [`QuoteRequest` (`35=R`), `Quote` (`35=S`), and `AcceptQuote` (`35=UA`)](/fix/rfq-messages), which are routed internally by Kalshi. * When trading via FIX, both `MassCancelRequest` and `CancelOrdersOnDisconnect` will target all exchange shards for the FIX session. * Automatic routing will incur an additional latency cost. * Subaccount balances are local to a specific exchange instance. * Order groups do not function across exchange instances. * [`KXMVECROSSCATEGORY-SHARD1-R`](https://demo-api.kalshi.co/trade-api/v2/multivariate_event_collections/KXMVECROSSCATEGORY-SHARD1-R) is live in demo for testing. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.