To (cause someone or something to) move or fall suddenly and often a long way forward, down, or into something. (Cambridge Dictionary)
To make a decision to do something, especially after thinking about it for a long time. (Cambridge Dictionary)
Jump or dive quickly and energetically. (Oxford Dictionaries)
Fall suddenly and uncontrollably. (Oxford Dictionaries)
To cause to penetrate or enter quickly and forcibly into something. (Merriam – Webster)
If something or someone plunges in a particular direction, especially into water, they fall, rush, or throw themselves in that direction. (Collins Dictionary)
Time To Plunge Into Stocks?