The selling of U.S. dollars to buy yuan is an attempt to prop up the Chinese currency. This could lead to a stronger yuan, which may positively impact Chinese stocks and, by extension, the FXI ETF, which tracks large-cap Chinese companies.

While the SPY ETF tracks the U.S. market, the global interconnectedness of markets means that significant moves in major economies like China can have ripple effects. However, the direct impact on SPY is likely to be minor.