An ETF has two prices. Its NAV — net asset value — is what its holdings are worth, divided by the number of units. Its market price is what buyers and sellers agree on the exchange. When the market price is above NAV it trades at a premium; below, at a discount.
Large dealers called authorised participants keep the two close: when the price drifts, they can create or redeem units with the fund and profit from closing the gap. Gaps still open when the fund's holdings trade while the exchange is shut — an Asian index during London hours, say — and in stressed markets, especially for bond ETFs, where they have at times been wide. The app shows your ETF's market price, not its NAV; the provider's website publishes both.
Authorised participants usually close small gaps like this. In stressed markets they can stay open.
Educational content only. It is not personal financial advice.