Snowball selling influences mortgage rates significantly by triggering a chain reaction in bond markets. As traders react to potential interest rate hikes from the Federal Reserve, expedited selling occurs, leading to falling bond prices and subsequently rising yields. This dynamic affects mortgage rates, typically pushing them upward, which in turn influences buyer behavior. A surge in rates can prompt buyers to act quickly to lock in lower financing costs, while sellers may adopt a cautious approach on pricing, impacting overall market activity.