Witching hour, in a financial context, is the final hour of daily trading in the stock market between the bond market close at 3 p.m. EST and the stock market close at 4 p.m.
Witching hour is characterized by greater volatility, which high-level professional traders and large institutions exploit for greater profits. On the third Friday of each financial quarter, triple witching hour occurs when stock index options, stock options and stock index futures all expire simultaneously and roll to the next series.
In a supernatural context, witching hour is the hour of the night when ghosts, demons, witches are thought to have the most power to interact with the human world. Most commonly, witching hour is thought to begin at midnight, although some paranormal afficionados consider 3 a.m. to be witching hour (sometimes known as the devil's hour or the dead hour). Some writers have identified witching hour as twilight while yet others have said it encompasses the entire night.
The first reference to witching hour is probably from Shakespeare, in this part of Hamlet's soliloquy on avenging his father's death:
Tis now the very witching time of night,
When churchyards yawn and hell itself breathes out
Contagion to this world: now could I drink hot blood,
And do such bitter business as the day
Would quake to look on.