Interest Rates: VGLT holds long-term Treasury bonds, so its price is highly sensitive to interest rate changes. When rates rise, VGLT's price typically falls, and vice versa.

Inflation Expectations: Rising inflation expectations often lead to higher interest rates, which negatively impacts VGLT's price. Conversely, falling inflation expectations can boost VGLT.

Economic Growth: Strong economic growth may lead to higher interest rates as the Federal Reserve tries to control inflation, potentially lowering VGLT's price. Weaker growth could push rates down, increasing VGLT's value.

Federal Reserve Policy: The Federal Reserve's monetary policy decisions, such as raising or lowering the federal funds rate and quantitative tightening, significantly influence Treasury yields and thus VGLT's price.

Geopolitical Events: Major global events and political instability can drive investors towards safer assets like Treasury bonds, potentially increasing demand and thus VGLT's price (flight to safety).

Supply of Treasury Bonds: An increase in the supply of new Treasury bonds can put downward pressure on bond prices, including those held by VGLT.