Ultimately the AP (authorized participant) is incentivized to make ETFs available because they get to use supply/demand imbalances as an arbitrage opportunity.
> The creation and redemption mechanisms help ETF shares to trade at a price close to the market value of their underlying assets. When ETF shares begin to trade at a price that is higher than the market value of their underlying assets (at a “premium”), APs may find it profitable to create ETF shares by buying the underlying securities and exchanging them for ETF shares, and then sell those shares into the market. Similarly, when ETF shares begin to trade at a price lower than the market value of their underlying assets (at a “discount”), APs may find it profitable to buy ETF shares in the secondary market and redeem them to the ETF in exchange for the underlying securities. These actions by APs, commonly described as “arbitrage opportunities,” help to keep the market-determined price of an ETF’s shares close to the market value of their underlying assets.
Ultimately the AP (authorized participant) is incentivized to make ETFs available because they get to use supply/demand imbalances as an arbitrage opportunity.
> The creation and redemption mechanisms help ETF shares to trade at a price close to the market value of their underlying assets. When ETF shares begin to trade at a price that is higher than the market value of their underlying assets (at a “premium”), APs may find it profitable to create ETF shares by buying the underlying securities and exchanging them for ETF shares, and then sell those shares into the market. Similarly, when ETF shares begin to trade at a price lower than the market value of their underlying assets (at a “discount”), APs may find it profitable to buy ETF shares in the secondary market and redeem them to the ETF in exchange for the underlying securities. These actions by APs, commonly described as “arbitrage opportunities,” help to keep the market-determined price of an ETF’s shares close to the market value of their underlying assets.
http://www.understandetfs.org/creation_redemption.html
My understanding is that volatility is good for ETF APs because there are more arbitrage opportunities.