oscillate
verb [ I ]
uk/ˈɒsɪleɪt/ usto move repeatedly from one position to another:
oscillate between sth and sth The stock has spent most of the past five years oscillating between $3 and $5.
The FTSE 100 index closed up 2.4%, having oscillated wildly throughout the week.
oscillation
noun [ C or U ]
a long period of oscillation between profit and loss