Impact of Adding Negatively Correlated Stock on Portfolio Risk

In the context of portfolio management, diversification is a key strategy employed to reduce risk. An investor has a portfolio consisting of five different stocks: Stock A, Stock B, Stock C, Stock D, and Stock E. Each stock has its own risk and return characteristics, and they are not perfectly correlated with each other.

Assuming the investor adds a sixth stock, Stock F, which is negatively correlated with all existing stocks, how will this addition most likely impact the overall portfolio risk?