SRP code before refactoring

TradeProcessor.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace SalesProcessor
{
  public class TradeProcessor
  {
    public void ProcessTrades(Stream stream)
    {
      // read rows
      var lines = new List<string>();
      using (var reader = new StreamReader(stream))
      {
        string line;
        while ((line = reader.ReadLine()) != null)
        {
          lines.Add(line);
        }
      }

      var trades = new List<TradeRecord>();

      var lineCount = 1;
      foreach (var fields in lines.Select(line => line.Split(new[] { ',' })))
      {
	      if (fields.Length != 3)
	      {
		      Console.WriteLine("WARN: Line {0} malformed. Only {1} field(s) found.", lineCount, fields.Length);
		      continue;
	      }

	      if (fields[0].Length != 6)
	      {
		      Console.WriteLine("WARN: Trade currencies on line {0} malformed: '{1}'", lineCount, fields[0]);
		      continue;
	      }

	      if (!int.TryParse(fields[1], out var tradeAmount))
	      {
		      Console.WriteLine("WARN: Trade amount on line {0} not a valid integer: '{1}'", lineCount, fields[1]);
	      }

	      if (!decimal.TryParse(fields[2], out var tradePrice))
	      {
		      Console.WriteLine("WARN: Trade price on line {0} not a valid decimal: '{1}'", lineCount, fields[2]);
	      }

	      var sourceCurrencyCode = fields[0].Substring(0, 3);
	      var destinationCurrencyCode = fields[0].Substring(3, 3);

	      // calculate values
	      var trade = new TradeRecord
	      {
		      SourceCurrency = sourceCurrencyCode,
		      DestinationCurrency = destinationCurrencyCode,
		      Lots = tradeAmount / LotSize,
		      Price = tradePrice
	      };

	      trades.Add(trade);

	      lineCount++;
      }

      using (var connection = new System.Data.SqlClient.SqlConnection("Data Source=(local);Initial Catalog=TradeDatabase;Integrated Security=True;"))
      {
        connection.Open();
        using (var transaction = connection.BeginTransaction())
        {
          foreach (var trade in trades)
          {
            var command = connection.CreateCommand();
            command.Transaction = transaction;
            command.CommandType = System.Data.CommandType.StoredProcedure;
            command.CommandText = "dbo.insert_trade";
            command.Parameters.AddWithValue("@sourceCurrency", trade.SourceCurrency);
            command.Parameters.AddWithValue("@destinationCurrency", trade.DestinationCurrency);
            command.Parameters.AddWithValue("@lots", trade.Lots);
            command.Parameters.AddWithValue("@price", trade.Price);

            command.ExecuteNonQuery();
          }

          transaction.Commit();
        }
        connection.Close();
      }

      Console.WriteLine("INFO: {0} trades processed", trades.Count);
    }

    private static float LotSize = 100000f;
  }
  internal class TradeRecord
  {
	  internal string DestinationCurrency;
	  internal float Lots;
	  internal decimal Price;
	  internal string SourceCurrency;
  }
}