The Dow is the "safest" market in the world - if it drops 4000 points, most other markets will lose 50% or more. That would require another 2008 style crash. I don't see that as a realistic probability.

Even if Europe implodes (unlikely), this would not cause a 4000 point loss in the Dow. Greece's GDP is less than the market cap of Apple, and China's growth swallows the entire GDP of Italy + Spain each and every year. The Fed is still very much in easing mode & now China is joining in. More likely that markets finish the year higher than lower - let alone down 4000 points.