Underlying Index Performance: The primary driver is the performance of the underlying index it tracks. If the index rises, the ETF price generally rises and vice versa.

Supply and Demand: Market demand for the ETF itself influences its price. High demand can push the price above its net asset value (NAV), creating a premium.

NAV: The Net Asset Value is a crucial factor, calculated based on the market value of the ETF's holdings. The ETF price tends to align with its NAV.

Expense Ratio: While not directly affecting daily price fluctuations, a higher expense ratio can indirectly impact returns over the long term, thus influencing investor sentiment.

Trading Volume & Liquidity: High liquidity allows for smoother trading and tighter bid-ask spreads, potentially making the ETF more attractive and maintaining price stability.

Market Sentiment: Broad market trends and investor sentiment towards the sector or asset class the ETF represents also affect its price. Positive sentiment increases the price.