Market Interest Rates: Rising rates generally decrease bond prices, affecting NPSAX's value, while falling rates tend to increase it.

Credit Quality: Downgrades in the creditworthiness of bonds held by NPSAX can lead to price declines, while upgrades can increase values.

Inflation Expectations: Higher anticipated inflation usually leads to lower bond prices as investors demand higher yields to compensate, thus impacting NPSAX negatively.

Economic Growth: A strong economy may reduce demand for bonds as investors shift to riskier assets, potentially lowering NPSAX's price.

Fund Management: The fund manager's skill in selecting and managing bonds directly impacts the fund's performance and thus its price.

Fund Expenses: The expense ratio and other costs associated with running NPSAX reduce its returns, thereby influencing its price compared to similar funds.

Supply and Demand: Higher demand for NPSAX can push its price up, while increased selling pressure can cause it to fall.