1 billion to 20 billion. If the market value of etf is too small, there is a risk of liquidation. If the scale is small, the liquidity will be poor and the order transaction efficiency will be low. The best is the scale of 65.438+0 billion to 20 billion. Exchange-traded open index securities investment fund (ETF), also known as "exchange-traded fund", is a fund that tracks the change of "underlying index" and is listed and traded on the stock exchange.