Underlying Asset Performance: WAT.PA ETF price mirrors the performance of its underlying assets, likely tracking an index. Positive performance in those assets leads to price increases, negative to decreases.

Supply and Demand: Higher demand for WAT.PA units drives prices up, and increased selling pressure forces prices down. Trading volume and investor sentiment are key indicators.

Net Asset Value (NAV): WAT.PA's market price should closely track its NAV. Significant deviations may create arbitrage opportunities, influencing the ETF's price.

Expense Ratio: While not directly affecting price, a higher expense ratio can indirectly impact investor demand for WAT.PA relative to similar, lower-cost ETFs, influencing its price over time.

Market Conditions: Broad market trends like economic growth, interest rates, and inflation can indirectly influence WAT.PA's price by affecting the sentiment towards its underlying assets.

Currency Fluctuations: For international ETFs like WAT.PA, currency fluctuations between the Euro and the currencies of the underlying assets can impact the Euro-denominated price.