Underlying Asset Performance: The primary driver is the performance of the underlying securities tracked by the ETF. If the constituent stocks rise, the ETF's price generally increases, and vice versa.

Supply and Demand: Market demand for the ETF influences its price. Higher demand tends to push the price up, while increased selling pressure can lower it.

Net Asset Value (NAV): The NAV, representing the total value of the ETF's holdings minus liabilities, is a key benchmark. The ETF's market price usually trades close to its NAV, but deviations can occur.

Market Sentiment: Overall investor sentiment towards the sectors or assets represented in the ETF impacts its price. Positive market sentiment typically drives prices higher.

Expense Ratio: While not directly affecting daily price swings, the expense ratio can indirectly influence the attractiveness of the ETF and thus its long-term price performance.

Trading Volume and Liquidity: Higher trading volume typically results in tighter bid-ask spreads and more efficient price discovery. Lower liquidity can lead to price volatility.

Changes in Index Composition: Adjustments to the underlying index can impact the ETF's price as fund managers rebalance their holdings to reflect the new composition.