TOKYO -- Bitcoin plunged last week, giving up 40% of its value from a record high of $19,783 per unit on Dec. 17. The selloff was exacerbated by retail investors in Japan, many of them leveraged, as they rushed to dump their holdings in a panic.
Curiously, though, it was the same bruised bunch who helped buoy the cyptocurrency after the selling had run its course. Given their growing influence, such investors are becoming known as "Mr. Watanabe," a variation of their relatives in the foreign-exchange market known as "Mrs. Watanabe."