Underlying Index Performance: VIOO tracks the S&P SmallCap 600 Index, so its price closely reflects the performance of these 600 smaller US companies. Strong overall performance in this segment drives VIOO's price up.

Economic Conditions: The health of the US economy significantly impacts small-cap companies. Factors like GDP growth, interest rates, and inflation influence their profitability and, consequently, VIOO's price.

Investor Sentiment: Broad market sentiment toward small-cap stocks affects demand for VIOO. Positive outlooks lead to increased buying pressure, pushing the price higher. Conversely, negative sentiment can cause sell-offs and price declines.

Sector Performance: Specific sectors within the S&P SmallCap 600 may experience disproportionate growth or decline, impacting VIOO. The ETF's allocation to these sectors determines the extent of the effect.

Interest Rates: Rising interest rates can negatively impact small-cap companies by increasing borrowing costs, potentially leading to lower profits and a decrease in VIOO's price.

Fund Flows: Large inflows of capital into VIOO can increase demand and drive the price up, while significant outflows can lead to selling pressure and price decreases.

Currency Fluctuations: While VIOO invests in US companies, currency fluctuations can indirectly affect its price. A stronger dollar might make US exports more expensive, potentially impacting the revenue of some small-cap companies and VIOO's performance.