Interest Rate Changes: Rising interest rates generally cause bond prices, including VBIIX, to fall, as newly issued bonds become more attractive. Conversely, falling interest rates usually lead to bond price increases.

Inflation Expectations: Higher inflation expectations can erode the real return on bonds, prompting investors to sell, which lowers bond prices. Lower inflation expectations often boost bond prices.

Credit Risk: Changes in the perceived creditworthiness of bond issuers within the VBIIX portfolio can affect its price. Downgrades may lead to price declines, while upgrades can increase prices.

Economic Growth: Stronger economic growth often leads to higher interest rates and inflation expectations, potentially decreasing bond prices. Weaker growth might have the opposite effect.

Market Sentiment: Investor risk appetite influences demand for bonds. During risk-off periods, investors may flock to safer assets like bonds, driving up prices. In risk-on environments, bond prices may decline.