At this time of year it is common for anyone who bought a stock at a higher price to sell it locking in a loss to go against their profits in income tax . 30 days later they can buy the stock back if they still want to own it .

Suppose you bought a PP at 1.25 . The stock is down either to Macro news , Sector news or slow assays  to say .30 . 100 thous shares sold into that price would get a 100 thous $ tax deduction . 

It use to be that this created the January  effect . Small stocks would run up on tax loss buy backs . However it has now moved forward in time as companies have tried to get ahead of each other .