# Symbols & tagging

Symbols let you filter precisely. Here's how they're formatted and assigned.

## Formats

| Array | Format | Examples |
| --- | --- | --- |
| `tickers` | Uppercase exchange ticker. Share classes use a dot. | `AAPL`, `BRK.B`, `SPY` |

Filters are case-insensitive: `tickers=aapl` works.

## How symbols are assigned

1. **From the source:** wire services and news providers often tag releases with tickers.
2. **From enrichment:** entities the model can confidently map to a listed company are added.

Passing mentions are usually not tagged. "Shares of Apple supplier X rose" is tagged `X`, not `AAPL`. For broader matching, combine a symbol filter with `q`.

## Coverage

Coverage is US-listed equities and ETFs. [GET /tickers](/docs/tickers) lists every symbol with at least one article. Publishers are on [coverage](/coverage) and [GET /sources](/docs/sources).