Underlying Holdings' Performance: QUS tracks an index of US stocks. If the prices of the companies within that index increase, the ETF's price tends to rise. Conversely, if the prices decline, the ETF's price will likely fall.

Supply and Demand: General investor sentiment towards US equities affects supply and demand for QUS. Higher demand generally drives the price up, while greater selling pressure pushes it down.

Expense Ratio: The ETF's expense ratio, though small, can impact its long-term performance. A higher expense ratio means slightly less return for investors, potentially influencing its relative attractiveness.

Tracking Error: How closely QUS mirrors its benchmark index can affect its price relative to its theoretical net asset value. Significant tracking error might make it less desirable to some investors.

Market Conditions: Broad economic factors, such as interest rate changes, inflation, and geopolitical events, can influence the overall stock market, and therefore QUS's price.