Fundamentally, MMSTX.US's price, like other money market funds, remains close to $1.00 per share. However, slight fluctuations occur due to several factors: Interest Rates: Rising interest rates generally increase the yield of the fund, potentially making it more attractive and causing minor price appreciation towards $1.00. Conversely, falling rates can decrease yield and cause slight price depreciation. Fund Expenses: Management fees and operational expenses impact the fund's net yield. Higher expenses can reduce the overall return, subtly affecting the share price relative to $1.00. Credit Quality of Holdings: The creditworthiness of the underlying securities (e.g., Treasury bills, commercial paper) influences perceived risk. Downgrades in credit ratings can lead to small price decreases. Supply and Demand: While money market funds aim for price stability, increased demand may slightly push the price above $1.00, and increased selling pressure may push it slightly below.