Underlying Asset Performance: The primary driver is the performance of the underlying securities the ETF tracks. A rise in these securities leads to a price increase, and vice-versa.

Supply and Demand: Market forces of supply and demand influence the ETF's price. Higher demand than supply will increase the price, while the reverse reduces it.

Market Sentiment: Overall market sentiment towards the underlying sector or asset class affects ETF prices. Positive sentiment boosts demand, increasing the price.

Expense Ratio: A lower expense ratio attracts more investors, potentially increasing demand and the ETF price. High expense ratios can deter investors.

Liquidity: Higher liquidity makes it easier to buy or sell the ETF, potentially increasing demand and stabilizing the price. Low liquidity can lead to price volatility.

Tracking Error: How closely the ETF's performance mirrors its benchmark index impacts investor confidence and demand, affecting the ETF's price.

Index Changes: Revisions or changes within the tracked index can create buying/selling pressure, affecting the ETF price.