S&P 500 Performance: SPXI11.SA aims to mirror the S&P 500, so its price directly reflects the index's movements. A rising S&P 500 typically boosts SPXI11.SA.

USD/BRL Exchange Rate: As SPXI11.SA holds assets denominated in USD, the exchange rate between the US dollar and Brazilian real significantly impacts its price. A stronger USD relative to the BRL increases the ETF's price in BRL terms.

Fund Expenses and Management Fees: The ETF's expense ratio and management fees are deducted from its returns, which subtly affects its price over time, reducing its overall performance relative to the underlying index.

Supply and Demand: Like any traded asset, SPXI11.SA's price is influenced by the supply of available units and the demand from investors. Higher demand tends to push the price up, while increased supply can lower it.

Investor Sentiment: Overall market sentiment towards risk assets, particularly US equities, plays a role. Positive sentiment can lead to increased investment in SPXI11.SA, driving up its price.