Etfs play the same way as stocks, with a minimum of 100 copies, and t+ 1, 10% rise and fall. The difference is that etf belongs to the category of index funds. It buys high-quality stocks representing the whole industry. When the relevant stocks go up, etf goes up, so it is actually a fund, but its advantages over ordinary funds are simple and direct, convenient and transparent, real-time trading, high throwing and low sucking. As for the stable profit of the operation, it is suggested that the grid should add positions, and the more it falls, the more it will buy until it is profitable, and it will not be delisted.