Is Bitcoin in a Bear Market When It's Still Up 1,500% for Year?

Bitcoin has yet to redefine the global payments system. But it could raise questions about how to define a bear market.

Stock strategists -- and financial journalists -- typically use a 20 percent tumble from a high as the trigger for calling a bear market. Bitcoin has met that description this week, according to Bloomberg’s composite price. The low for Wednesday was 20 percent below the record, set way back ... on Monday. It has continued to slide.