The golden cross is a technical indicator that occurs when a stock's 50-day moving average crosses above its 200-day moving average. This is generally considered a bullish signal, as it indicates a potential change in the long-term trend. In the case of CoStar Gr, the formation of a golden cross could lead to an increase in the stock price in the short term. However, it is important to note that seasoned investors do not blindly trade golden crosses and consider other factors such as price levels and company fundamentals before making decisions.