The article introduces a new method for studying how stock prices change over time. By using a special computer program called a particle filter, researchers can better understand the factors that affect stock market volatility, like sudden jumps in prices and the impact of borrowing money to invest. They found that including these factors in their model leads to more accurate predictions of future stock prices. They also created a new model called SV-GARCH, which combines two existing models to make even better predictions. Overall, the study shows that considering leverage and jumps in stock prices is important for accurately modeling how stock prices change over time.