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Will an ETF increase in price if an underlying stock increases in price
The ETF supply management policy is arcane.  ETFs are not allowed to directly arbitrage their holdings against the market.  Other firms must handle redemptions & deposits.  This makes ETFs slightly costlier than the assets held. For ETFs with liquid holdings, its price will rarely vary relative to the holdings, slippage of the ETF's holdings management notwithstanding.  This is because the firms responsible for depositing & redeeming will arbitrage their equivalent holdings of the ETF assets' prices with the ETF price. For ETFs with illiquid holdings, such as emerging markets, the ETF can vary between trades of the holdings.  This will present sometimes large variations between the last price of the ETF vs the last prices of its holdings. If an ETF is shunned, its supply of holdings will simply drop and vice versa.