yo-yo

1. noun

a) A toy consisting of a spheroidal or cylindrical spindle having a circular groove in which string is wound; it is used by holding the string in the fingers and reeling the spindle up and down by movements of the wrist.

It is hard to watch the management for very long and not conclude that the place is run by a bunch of yo-yos.

b) A volatile market that moves up and down.

2. verb

To vacillate; to move up and down.