Interest Rates: Rising interest rates generally decrease bond prices, including those held by JNNRX, while falling rates increase them.

Credit Risk: Downgrades in credit ratings of issuers whose bonds are held by the fund can lower its value, and upgrades can increase it.

Inflation Expectations: Higher inflation expectations can lead to lower bond prices as investors demand higher yields, negatively impacting JNNRX.

Economic Growth: Strong economic growth can lead to higher interest rates and potentially lower bond prices, conversely slower growth can lower rates and increase prices.

Fund Management: The skill and strategy of the fund managers in selecting and trading bonds can impact the fund's overall performance and price.

Supply and Demand: Increased demand for JNNRX can drive up its price, while increased selling pressure can lower it.

Market Sentiment: General investor sentiment towards fixed income investments can influence the fund's price, positive sentiment can increase prices and negative sentiment can decrease prices.

Expense Ratio: The fund's expense ratio can indirectly affect its returns, as higher fees reduce the net return to investors.

Call Features: Callable bonds held by the fund can be called away by the issuer if interest rates decline, potentially limiting upside gains for JNNRX.