Underlying Assets: GMAR's price is directly tied to the performance of its underlying assets, which are primarily U.S. Treasury bonds of varying maturities. Their prices fluctuate with interest rate changes.

Interest Rate Movements: As a bond ETF, GMAR is highly sensitive to interest rate shifts. Rising rates generally cause bond prices, and thus GMAR's value, to decline, and vice versa.

Inflation Expectations: Inflation erodes the purchasing power of fixed-income securities. Higher inflation expectations can lead to lower bond prices and negatively impact GMAR.

Economic Growth: Strong economic growth often leads to higher interest rates, impacting bond yields and potentially reducing GMAR's price. Slower growth might have the opposite effect.

Federal Reserve Policy: Actions by the Federal Reserve, such as adjusting the federal funds rate or implementing quantitative easing/tightening, significantly influence interest rates and bond market conditions, affecting GMAR.

Supply and Demand: The fundamental law of supply and demand also applies. Increased investor demand for GMAR can push its price higher, while increased selling pressure can lower it.

Credit Risk Perception: Although GMAR primarily holds U.S. Treasury bonds, which are considered virtually risk-free, changes in the perceived creditworthiness of the U.S. government, however unlikely, could affect its price.