It has been a rough year for the commodity chemical giant Dow (DOW -1.29%). The stock is down about 23% year to date at the time of this writing -- and 13% in just the past month. In November, Dow was kicked out of the Dow Jones Industrial Average and replaced by Sherwin-Williams. The downward moves have pushed the chemical maker's dividend yield up to 6.7%.Here's what's driving the sell-off in Dow's shares and why it may be a high-yield dividend stock worth buying now. Challenges are building up for DowDow ...