Underlying Asset Performance: 00861.TW tracks a specific index, thus its price heavily depends on the performance of the underlying assets within that index. Positive performance of those assets generally increases the ETF's price, while negative performance decreases it. Supply and Demand: Like any traded asset, the supply of 00861.TW shares and the demand for them influence its price. Higher demand relative to supply pushes the price up, and vice versa. Market Sentiment: Overall investor sentiment towards the market, the sector the ETF represents, or the specific companies within the index can significantly impact the ETF's price. Positive sentiment increases demand, pushing prices higher. Economic Conditions: Broad economic factors such as interest rates, inflation, and GDP growth can affect the performance of companies within the index and consequently the ETF's price. Currency Fluctuations: For international ETFs or those holding assets denominated in other currencies, exchange rate fluctuations can impact the value of the ETF when expressed in the local currency. Expense Ratio and Trading Costs: While not directly determining the price, the ETF's expense ratio and any trading costs associated with buying or selling shares can indirectly impact investor returns and therefore affect its attractiveness.