I was just looking at a piece of code for hedging and saw 3 bugs and numerous hacks to work around flaws. It doesn't surprise me that third time lucky it blows up.

class HedgingJob
  
  @queue = :normal
  
  def self.perform
    
    confidence_level = Setting.where(:key => "confidence_level").first.value.to_f
    surplus = Setting.where(:key => "surplus").first.value.to_f
    if Setting.where(:key => "buy_factor").first
      buy_factor = Setting.where(:key => "buy_factor").first.value.to_f
      sell_factor = Setting.where(:key => "sell_factor").first.value.to_f
    else
      buy_factor = 1
      sell_factor = 1
    end
    
    if surplus.abs > confidence_level
      amount = surplus.abs - confidence_level
      if surplus > 0
        amount *= buy_factor
        price = Ticker.last_tick("BTCUSD").selling * 1.02
        response = MtGox.buy!(amount, price)
        Setting.change_surplus(0-amount/buy_factor)
      else
        amount *= sell_factor
        price = Ticker.last_tick("BTCUSD").buying / 1.02
        response = MtGox.sell!(amount, price)
        amount = 0 - amount
        Setting.change_surplus(0-amount/sell_factor)
      end
      
      Trade.create(:amount => amount, :price => price, :response => response.to_s[0..253])
    
    end
    
    
    
  end
  
end