Brenda the reason you are seeing that leverage is because in your code you ask it to buy 100% of you portfolio value for each stock.

 Iterate over the list of stocks  
    for stock in context.stocks:  
        current_position = context.portfolio.positions[stock].amount  
        # Close position for the stock when the MACD signal is negative and we own shares.  
        if signal[stock] < 0.1 and current_position > 0:  
            order_target(stock, 0)  
        # Enter the position for the stock when the MACD signal is positive and  
        # our portfolio shares are 0.  
        elif signal[stock] > 0.05 and current_position == 0:  
            order_target_percent(stock, 1 - current_position)  

So you have 3 securities in context.stocks and you iterate through each of them, your buy logic is what is messing you up. To enter a position you require that the signal is greater than 0.05 and you currently have 0 positions, are as your code says current_position == 0. Well when you place the order you choose a portfolio weighting of 1 - current_position well that statement will always evaluate to 1, since by definition the only way to get to the order statement is by having a current position of 0. Consequently you will always place an order for 100% of your portfolio value for each stock.

I've attached a backtest where I changed it to just hold an equal weighting of each security, log the leverage, and use schedule_function which is a more robust way to trade than with custom date logic as you have it now.