reach an upper limit
to top out / plateau
To maintain the same status
remain stable
To move downwards
fall
To be unstable
fluctuate
a downward tendency
downtrend
To fall quickly and suddenly
plummet
to rise quickly or make extremely quick progress in a short amount of time
rocket
used to refer to the lowest point on a graph
hit a low
an upward tendency
uptrend
Reaching the highest point on the graph
peak
a sudden an rapid change
sharp (increase or decrease)
a sudden large increase, typically a temporary one.
surge
To cause something to increase
raise
a company controlled by a holding company.
a subsidiary