peak of a financial bubble; bubble peak
Refers specifically to the height of an economic bubble, most commonly the Japanese asset price bubble around 1990.
At the peak of the bubble, everyone was investing in stocks and land.
In Japan at the bubble peak, the abnormal surge in land prices became a social problem.
バブル崩壊 means the bursting of the bubble, the event that follows the peak.
Compound of バブル (bubble, from English) + 絶頂期 (peak period). The term is closely associated with the Japanese asset price bubble of the late 1980s.