> ## Documentation Index
> Fetch the complete documentation index at: https://docs.struct.to/llms.txt
> Use this file to discover all available pages before exploring further.

# Event Holder Metrics

> Fire a webhook with holder counts for specific events as they change.

<Note>
  **Event:** `event_holder_metrics` \
  **Cost:** 0.025 credits per delivery
</Note>

Fires with the updated holder count for the events you subscribe to. The full payload schema is in the auto-generated [Event Holder Metrics callback](/api-reference/webhook-callbacks/event-holder-metrics-callback) reference; this page documents the filters and matching behavior.

## When to use this

* Track the number of distinct wallets participating in an event across all its markets.
* Watch event-level participation grow or shrink over time.
* Compare holder breadth between events you follow.

## Subscription filters

Add these to the `filters` object when you create the subscription.

| Filter        | Type      | Required | Description                                   |
| ------------- | --------- | -------- | --------------------------------------------- |
| `event_slugs` | string\[] | Yes      | Event slugs to track (at least one, max 500). |

Unlike the optional filters on the PnL webhooks, `event_slugs` is required: a subscription must name at least one event to receive deliveries.

## Example

```json theme={null}
{
  "url": "https://your-server.com/webhooks",
  "event": "event_holder_metrics",
  "filters": {
    "event_slugs": ["us-presidential-election-2028"]
  }
}
```

## Notes

* The payload is an `EventHolderMetricsRow` carrying the event slug and its holder count.
* Each subscription accepts up to 500 event slugs.