The exchange-traded fund industry is poised for explosive growth with a rule change from the Securities and Exchange Commission (SEC) potentially doubling the number of available ETFs within just one month. Fund expert Dave Nadig warns that this surge could create an overwhelming challenge for investors as the current market of 4,000 ETFs may balloon to over 7,000. This expansion is due in part to mutual fund managers securing approval to offer ETF versions of existing funds, potentially adding 3,000 new products. This influx has already triggered a rush with 400 new ETFs launching this year alone across various strategies from single-stock funds to income-generating products.