Exchange-traded funds have crossed a symbolic threshold in the United States, with more than 4,300 products now listed—surpassing the roughly 4,200 publicly traded domestic stocks for the first time, according to Bloomberg data. The milestone follows an unrelenting pace of fund launches as issuers rush to capture investor demand for increasingly specialized and thematic strategies. Investor appetite remains robust. ETF inflows reached about $750 billion through late August, putting the industry on track to top $1 trillion in net creations for a second straight year. The torrent of new products and assets is expanding choice for retail and institutional buyers, but advisers say the sheer volume of offerings is making portfolio construction and due diligence more complex.