Underlying Asset Performance: The price of 00921.TW is directly linked to the performance of the underlying companies it tracks. If these companies perform well, the ETF's price will likely increase and vice versa.

Supply and Demand: General market supply and demand for the ETF itself also plays a role. Higher demand relative to supply leads to price increases, while the opposite causes prices to decrease.

Investor Sentiment: Overall market sentiment and investor confidence towards the tech sector, as 00921.TW tracks related companies, will influence buying and selling decisions.

Expense Ratio: The ETF's expense ratio, which is the annual fee charged to manage the fund, indirectly impacts its overall return and attractiveness to investors. Higher fees can deter some.

Economic Conditions: Macroeconomic factors such as interest rates, inflation, and economic growth can affect the performance of the underlying companies and, consequently, the ETF.

Currency Exchange Rates: Changes in the exchange rate between the New Taiwan Dollar (TWD) and other currencies can influence the attractiveness of the ETF to foreign investors.