Capitulation is best summarized as panic selling. Capitulation is the final phase in an extreme downtrend when stock owners are willing to sell out at any price. Capitulation is the end of a downtrend as a result of this panic selling. During capitulation, there is almost a complete lack of buyers, which creates a vacuum of selling.
Example of capitulation:
This index saw capitulation as prices moved lower and accelerated in their descent. Capitulation ends with a volume climax as price moves virtually straight down.
Capitulation is the opposite of a parabolic uptrend, and often marks a lasting low on extremely heavy volume.