Tengo el siguiente JSON:

{"positions":{"position":[{"cost_basis":102.20000,"date_acquired":"2013-11-18T19
:54:13.730Z","id":192,"quantity":2.00000,"symbol":"C"},{"cost_basis":121.50990,"
date_acquired":"2013-11-20T17:43:41.737Z","id":199,"quantity":1.00000,"symbol":"
TSLA"}]}}

Estoy usando JSON.NET (paquete de Newtonsoft) para deserializar mi objeto de datos.

List<position> position = JsonConvert.DeserializeObject<List<position>>(responsebody);
foreach (position item in listObj)
{
 Console.WriteLine("Test : ", item.id);
}


public class positions
    {
        List<position> position { get; set; }

    }

public class position
    {
        public float cost_basis { get; set; }
        public DateTime date_acquired { get; set; }
        public int id { get; set; }
        public int quantity { get; set; }
        public string symbol { get; set; }

    }

Cuando intento deserializar el objeto, aparece el siguiente error.

Unhandled Exception: Newtonsoft.Json.JsonSerializationException: Cannot deserial
ize the current JSON object (e.g. {"name":"value"}) into type 'System.Collection
s.Generic.List`1[ApiPost.position]' because the type requires a JSON array (e.g.
 [1,2,3]) to deserialize correctly.
To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or chang
e the deserialized type so that it is a normal .NET type (e.g. not a primitive t
ype like integer, not a collection type like an array or List<T>) that can be de
serialized from a JSON object. JsonObjectAttribute can also be added to the type
 to force it to deserialize from a JSON object.
Path 'positions', line 1, position 13.
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(Js
onReader reader, Type objectType, JsonContract contract, JsonProperty member, Js
onContainerContract containerContract, JsonProperty containerMember, Object exis
tingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInte
rnal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty mem
ber, JsonContainerContract containerContract, JsonProperty containerMember, Obje
ct existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(Jso
nReader reader, Type objectType, Boolean checkAdditionalContent)
   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type
 objectType)
   at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, Jso
nSerializerSettings settings)
   at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSeriali
zerSettings settings)