Which of the following is NOT considered a driving factor of market prices?

Speculative trading is actually a significant part of market dynamics and can influence price movements significantly. It involves traders making bets on the direction of price movements based on market sentiment, trends, or other strategies. Speculative trading allows for liquidity in the markets, which is crucial for price discovery and can lead to dramatic price changes based on traders' perceptions and actions.

Investor decisions, government policy, and international trade relations are all foundational elements that can drive market prices. Investor decisions encompass the buying and selling actions of all market participants, reflecting their outlook on the economy and individual securities. Government policy can directly impact economic conditions and overall market stability through regulations, fiscal measures, and monetary policy. Similarly, international trade relations can affect a country's economic environment, influencing everything from currency valuations to the profitability of various sectors, thereby driving prices up or down based on the flow of goods and services across borders.

Thus, while speculative trading is an integral part of how markets operate, it's part of a broader spectrum of factors, rather than a driving force on its own.