ETFs are offered by Asset Management Companies (AMCs). You can invest in ETFs either at the time of the New Fund Offering (NFO) or buy them directly from the secondary market.\r\rNew Fund Offering (NFO): The AMC offering the ETF announces the NFO dates. You can subscribe to the ETF by filling the application form. Once the NFO closes, the AMC will allot the ETF units.\rSecondary market: Once the NFO closes and the allotment to subscribers is completed, the ETF units are listed on stock exchanges like BSE and NSE. The trading of ETF units happens during market hours, just like equity shares. You can buy the ETF units through your stockbroker by placing an order from your trading account.