The core idea
Orders from buyers and sellers meet in the market. New information changes what people are willing to pay.
A little more context
Prices reflect expectations, not just results. A profitable quarter may disappoint investors who expected more.
What to remember
Volatility measures the size of price changes over a period. It is one aspect of risk, not a complete measure of possible loss.
Pause and reflect: how would you explain this idea to someone who has never invested?