Operating leverage
When a large part of a company's costs is fixed, profit grows faster than revenue. It works in both directions: when revenue falls, profit falls even faster.
Simple example
A company has $100 of revenue, $60 of fixed costs and $20 of costs that grow with sales, so $20 of profit. If revenue rises 10% to $110, costs rise only to $82, and profit jumps 40% to $28.