Generally speaking, the stock market can reflect the economic situation of a country or region, so can foreign exchange. Usually, foreign capital attacks the currency of a place or country by suppressing foreign exchange, thus hitting their economy. When the economy is depressed, the stock market will naturally plummet ... and vice versa. If a country's economic strength develops at a high speed, the stock market will naturally soar, and at the same time, the value of its own currency will continue to increase, which is roughly what this means. Moreover, the two markets complement each other and have the same direction. For example, the earthquake in Japan affected the economy, and the stock market and foreign exchange market plummeted at the same time. Although it was not man-made reasons, the reasons were the same.

According to my understanding of the plot, Seth and Fang's last money is not enough for them to act in two markets at the same time. They can only choose one, but controlling one market means controlling two markets. If Fang Xiaxin doesn't move or both sides bet on Seth, he will run, but if Fang Xiaxin controls a market, no matter which side Seth takes, he will die.