diff --git a/ByBit.Net/BybitAuthenticationProvider.cs b/ByBit.Net/BybitAuthenticationProvider.cs
index abc210c7..2842a894 100644
--- a/ByBit.Net/BybitAuthenticationProvider.cs
+++ b/ByBit.Net/BybitAuthenticationProvider.cs
@@ -9,6 +9,7 @@
 using System.Globalization;
 using Bybit.Net.Clients.V5;
 using System.Text;
+using Newtonsoft.Json;
 
 namespace Bybit.Net
 {
@@ -33,7 +34,7 @@ public override void AuthenticateRequest(RestApiClient apiClient, Uri uri, HttpM
             var timestamp = DateTimeConverter.ConvertToMilliseconds(GetTimestamp(apiClient).AddMilliseconds(-1000)).Value.ToString(CultureInfo.InvariantCulture);
             if (apiClient is BybitRestClientCopyTradingApi || apiClient is BybitRestClientApi)
             {
-                var signPayload = parameterPosition == HttpMethodParameterPosition.InUri ? uri.SetParameters(parameters, arraySerialization).Query.Replace("?", "") : parameters.ToFormData();
+                var signPayload = parameterPosition == HttpMethodParameterPosition.InUri ? uri.SetParameters(parameters, arraySerialization).Query.Replace("?", "") : apiClient.requestBodyFormat == RequestBodyFormat.FormData ? parameters.ToFormData() : JsonConvert.SerializeObject(parameters);
                 var key = _credentials.Key!.GetString();
                 var recvWindow = 5000;
                 var payload = timestamp + key + recvWindow + signPayload;
diff --git a/ByBit.Net/Clients/V5/BybitRestClientApi.cs b/ByBit.Net/Clients/V5/BybitRestClientApi.cs
index 67336e8f..7bf9e5df 100644
--- a/ByBit.Net/Clients/V5/BybitRestClientApi.cs
+++ b/ByBit.Net/Clients/V5/BybitRestClientApi.cs
@@ -50,7 +50,7 @@ internal BybitRestClientApi(ILogger logger, HttpClient? httpClient, BybitRestOpt
             ExchangeData = new BybitRestClientApiExchangeData(this);
             Trading = new BybitRestClientApiTrading(this);
 
-            requestBodyFormat = RequestBodyFormat.FormData;
+            requestBodyFormat = RequestBodyFormat.Json;
             ParameterPositions[HttpMethod.Delete] = HttpMethodParameterPosition.InUri;
         }
         #endregion