As DIA tracks the Dow Jones Industrial Average, its performance is closely tied to investor sentiment regarding monetary policy. The Fed's decision to leave rates unchanged may have led to uncertainty or disappointment among investors who were anticipating changes, thus negatively impacting DIA's price in the short term.

IWM is sensitive to changes in interest rates due to the higher debt levels often carried by small-cap companies. The Fed's decision to leave rates unchanged could signal slower economic growth, which may disproportionately affect small caps, leading to a short-term negative impact on IWM's price.

QQQ, which includes many growth and tech stocks, is often more volatile in response to interest rate decisions. The Fed's choice to leave rates unchanged could be interpreted as a lack of confidence in the economy, potentially reducing investor appetite for riskier assets like tech stocks, thus affecting QQQ negatively in the short term.

SPY tracks a broad range of large-cap stocks and is a bellwether for the overall market. The Fed's decision to not change interest rates may have led to a negative market reaction due to potential concerns over economic growth and inflation, which in turn affects SPY's short-term price movement.