Interest Rates: Changes in prevailing interest rates, particularly short-term rates, directly impact the yield and therefore the price of money market funds like HEWXX.US.

Credit Risk: Perceived creditworthiness of the issuers of securities held within the fund, such as government or corporate debt, affects the price. Higher risk leads to lower prices.

Economic Conditions: Overall economic health, including inflation, GDP growth, and unemployment, influences investor sentiment and demand for assets like HEWXX.US.

Fund Management: Decisions made by the fund's managers regarding asset allocation, security selection, and expense ratios can impact the fund's performance and price.

Supply and Demand: Investor demand for HEWXX.US relative to its supply of shares influences the market price, similar to any other traded asset.

Market Sentiment: General investor confidence or fear in the financial markets can indirectly affect the attractiveness and thus the price of safer assets like money market funds.