Net Asset Value (NAV): MXISX's price directly reflects its NAV, calculated by dividing the fund's total assets (minus liabilities) by the number of outstanding shares.

Underlying Bond Market: As a bond fund, MXISX's value is heavily influenced by interest rate movements and credit spreads in the bond market. Rising rates typically lower bond prices and NAV.

Credit Quality: Changes in the perceived creditworthiness of the bonds held in MXISX's portfolio will affect its price. Downgrades can lead to price decreases.

Fund Flows: Significant inflows or outflows of money into or out of MXISX can impact its NAV, particularly if the fund manager needs to buy or sell assets quickly.

Expense Ratio: While not directly affecting daily price changes, the expense ratio reduces the fund's overall returns and impacts long-term price appreciation.

Inflation Expectations: Changes in inflation expectations can influence interest rates and bond yields, thereby affecting MXISX's value. Higher inflation expectations often lead to higher interest rates.