Inheritance: IComparable
 public void RemoveMarketNewsItem(MarketNewsItem item)
 {
     if (_marketNewsItems != null)
     {
         _marketNewsItems.Remove(item);
     }
 }
        public void AddMarketNewsItem(MarketNewsItem item)
        {
            if (_marketNewsItems == null)
            {
                _marketNewsItems = new List <MarketNewsItem>();
            }

            _marketNewsItems.Add(item);

            LastUpdated = DateTime.Now;
        }