If we want to hedge against systemic risks, we should short the stock index, such as short the index of large-cap stocks, or short the index of buying stocks, but this means hedging against systemic risks.

Beta coefficient refers to the correlation of individual stocks. For example, under certain conditions, if the profitability of A-share listed companies is good, then B is relatively poor, B is good, and A is poor, then these two stocks have a certain beta coefficient, and buying these two stocks at the same time can wash away the risk. Therefore, the only way to adjust the beta coefficient is to do statistics and then find out the correlation between the stock and other stocks. Of course, this work is the most complicated problem that stock analysts have to solve.