The price of an ETF is determined by share prices of companies present in it. The units are created by an entity called a market maker. Demand and supply don’t affect ETFs as they affect shares, the ETF changes when a single big (highest weighted) share is affected or when all of the shares are affected. Investors can buy and sell ETFs whenever they want during trading hours. Like a stock, each ETF has a ticker symbol and a price that changes in real-time.