Pre-approved group of institutional firms who enter into an agreement with the ETF sponsor such as Blackrock/iShares. APs offer a basket of securities (or receive a basket of securities) from the ETF sponsor in exchange for ETF shares. APs may create or redeem (buy or sell) ETFs on behalf of their clients, use them for internal use or arbitrage the price of the ETF against the value of the basket of shares that is being created/redeemed. When the AP creates/redeems ETF shares with the ETF sponsor, it is considered the primary market.