1opening price — the first traded price when the market opens (used as a reference for that day's trading)
今日の株は始値より上で取引を終えた。
Today's stock finished trading above its opening price.
始値が前日の終値を大きく下回った。
The opening price fell well below the previous day's closing price.
始値は市場の開きの瞬間の価格だ。
The opening price is the price at the moment the market opens.