noun
ceiling price; price cap
Financial term for the maximum allowable or expected price, often set by regulation or market conditions.
政府はガソリンの天井値を設定した。
The government set a ceiling price for gasoline.
この株の天井値はいくらですか。
What is the ceiling price for this stock?
底値 is the opposite: 'floor price' or 'bottom price', the minimum price level.
Compound of 天井 (ceiling) + 値 (price). The metaphor of a ceiling as an upper limit is straightforward.