Which option is NOT a factor affecting a currency's supply or demand?

The option relating to stock market performance is not considered a direct factor affecting a currency's supply or demand. While stock market performance can indirectly influence currency values—such as through investor sentiment or overall economic health—it is not a fundamental determinant like interest rates, government policy, or speculative trading.

Interest rates have a direct impact on currency value because higher rates tend to attract foreign capital, increasing demand for that currency. Government policy, including fiscal and monetary measures, also plays a critical role in shaping a currency's desirability; for instance, interventions by the central bank can influence inflation and overall confidence in the economy. Speculative trading contributes significantly to currency fluctuations, as traders act on their perceptions of future currency movements based on various factors.

In contrast, while stock market performance can reflect economic conditions that might impact currency indirectly, it does not directly dictate the supply and demand dynamics of a currency in the way the other options do.