# Expirations

Retrieve the list of expiration dates that have listed options for an underlying symbol.

## Making Requests

Use `GetExpirationsAsync` on the `Options` resource.

```csharp
Task<OptionsExpirationsResponse> GetExpirationsAsync(
    string symbol, decimal? strike = null, DateOnly? date = null,
    MarketDataRequestOptions? options = null, CancellationToken cancellationToken = default)
Task<OptionsExpirationsResponse> GetExpirationsAsync(OptionsExpirationsRequest request, ...)
```

### OptionsExpirationsRequest

```csharp
new OptionsExpirationsRequest(string symbol)
{
    Strike = decimal,   // only expirations that list this strike
    Date = DateOnly     // expirations available as of this historical date
}
```

#### Returns

`OptionsExpirationsResponse` wrapping `IReadOnlyList<DateTimeOffset>` — one entry per expiration date, in ascending order.

## Examples

```csharp
using MarketDataApp;

using var client = await MarketDataClient.CreateAsync();

var expirations = await client.Options.GetExpirationsAsync("AAPL");
Console.WriteLine($"{expirations.Values.Count} expirations; next: {expirations.Values[0]:yyyy-MM-dd}");

// Only expirations that list the 200 strike.
var atStrike = await client.Options.GetExpirationsAsync("AAPL", strike: 200m);
```

For CSV output, call `client.Options.GetExpirationsCsvAsync(...)` and read `.Csv`. See [Settings](https://www.marketdata.app/docs/sdk/csharp/settings#csv-output).