Underlying Asset Performance: The value of the securities held within the ETF directly impacts its price. A rise in the value of the included stocks or bonds will generally lead to a rise in the ETF's price.

Supply and Demand: Market forces play a significant role. Increased demand for the ETF typically drives the price up, while increased supply can cause it to fall.

Net Asset Value (NAV): The NAV, calculated by dividing the total value of the ETF's holdings by the number of outstanding shares, serves as a benchmark for the ETF's market price. Discrepancies between the NAV and the market price can create arbitrage opportunities.

Expense Ratio: While not a direct influence on daily price fluctuations, a higher expense ratio can reduce the overall return of the ETF, making it less attractive to investors compared to similar, lower-cost ETFs.

Tracking Error: The ETF's ability to accurately track its benchmark index affects its appeal. Higher tracking error might lead investors to choose a more precise ETF, affecting its price.

Market Sentiment: General investor optimism or pessimism can significantly influence the price of the ETF, particularly during periods of high market volatility.

Index Composition Changes: Modifications to the underlying index the ETF tracks can lead to price adjustments as the fund rebalances its holdings to match the new index composition.