Underlying Asset Performance: The primary driver is the performance of the underlying securities the ETF tracks. If the securities in the index rise, the ETF price tends to increase, and vice versa.

Supply and Demand: Market forces of supply and demand for the ETF units themselves influence its price. Higher demand can lead to price increases, while increased supply can cause decreases.

Index Composition Changes: Changes in the composition of the tracked index, such as additions or deletions of constituent stocks, can impact the ETF's price.

Expense Ratio & Trading Costs: The ETF's expense ratio and trading costs can affect its price performance over time, relative to the underlying index returns.

Market Sentiment: Overall market sentiment, whether bullish or bearish, can impact the trading activity and therefore, the ETF's price.

Economic Factors: Macroeconomic factors like interest rates, inflation, and GDP growth can influence the performance of the underlying assets and, consequently, the ETF's price.

Fund Flows: Significant inflows into or outflows from the ETF can impact its price, especially for smaller or less liquid ETFs.

Liquidity of Underlying Assets: The liquidity of the underlying securities held by the ETF can affect its pricing efficiency and tracking accuracy.

Arbitrage: Arbitrage activities by market participants help keep the ETF's price aligned with the net asset value (NAV) of its holdings. Differences between the ETF price and NAV create arbitrage opportunities that influence the price.