dead cat bounce
A sign that something is healthy or recovering, when in fact the thing is already on its way to ruin, collapse, or stagnation. Used particularly in reference to financial issues. (Based on the figurative notion that a dead cat will still bounce after a large fall.) Analysts are warning investors that the sudden spike in the currency's value is a dead-cat bounce, a natural and predictable rally after a heavy sell-off.
n. a small, knee-jerk rally in one of the financial markets. (A dead cat—or any other animal—will bounce only slightly after being dropped. Refers to a stock index or security price that bounces up only slightly after a precipitous fall. Securities market.) The whole market gave only a deadcat bounce after the string of losses this last week.