Economic conditions: General economic health, including inflation, interest rates, and GDP growth, can affect overall market sentiment and influence investor behavior in bond markets.

Interest rate changes: Rising interest rates typically cause bond prices to fall, while falling interest rates generally cause bond prices to rise. This is because new bonds offer higher or lower yields.

Credit risk: The perceived creditworthiness of the bond issuers (in this case, primarily municipalities) affects the prices. Downgrades in credit ratings can lower prices, while upgrades may raise them.

Market liquidity: The ease with which bonds can be bought or sold influences price. Lower liquidity can increase price volatility and potentially widen the bid-ask spread.

Supply and demand: The balance between the supply of municipal bonds and the demand from investors affects prices. Increased supply relative to demand can lower prices.

Tax law changes: Changes in tax laws affecting the tax-exempt status of municipal bonds can affect their attractiveness to investors and, consequently, their prices.