RE:QuestionThis is why:
(Source: https://www.randomlengths.com/Woodwire/RL-Lbr-Pnl/ )
Panel prices (and this includes OSB prices) are down over $100 from their third quarter peaks. Q4 2017 and Q1 2018 earnings will undoubtedly suffer. Nevertheless, the market's reaction does seem to be exagerated. The steep slide started the day before the ex-dividend date and continued unabated. I suspect that much of the current trades is by day traders and shorters; this is a recipe for high volatility.
In any case, good luck to all.