Underlying Asset Performance: The primary driver is the performance of the assets the ETF tracks. If the underlying stocks or index rise, the ETF's price generally increases, and vice-versa.

Supply and Demand: Market forces of supply and demand impact ETF price. Higher demand than supply pushes the price up, while more sellers than buyers lower the price.

Net Asset Value (NAV): The NAV, reflecting the total value of underlying assets minus liabilities, serves as a benchmark. The market price tends to stay close to the NAV.

Investor Sentiment: Overall market sentiment, whether positive or negative, greatly influences investor behavior and ETF prices. Positive sentiment boosts buying pressure.

Market Volatility: Higher volatility in the underlying assets can lead to wider price fluctuations in the ETF. Periods of uncertainty increase price swings.

Dividend Payments: Dividends from the underlying stocks get passed on to ETF holders. The ETF's price might adjust slightly on ex-dividend dates.

Expense Ratio: The expense ratio, the ETF's operating cost, can subtly affect its price. Higher expenses could lead to a slightly lower return for investors.

Interest Rates: Changes in interest rates can indirectly impact stock valuations, consequently affecting ETF prices. Higher rates can sometimes pressure stock prices.

Economic Factors: Broad economic indicators such as inflation, GDP growth, and unemployment rates can influence investor confidence and ETF valuations.

Currency Fluctuations: If the ETF holds assets denominated in foreign currencies, changes in exchange rates can affect the ETF's price, especially for international ETFs.