tumble(о ценах, курсах акций и т.п.: Global stock markets tumble and oil soars after Russia moves troops into Ukraine • European shares tumble at the open)
equity floor(An agreement in which one party agrees to pay the other at specific time periods if a specific stock market benchmark falls below a predetermined level Taras)
dead cat bounce(A derogatory term used on the stock exchange to describe a huge decline in the value of a stock, usually a share, which is immediately followed by a temporary rise in price before continuing to fall. Interex)