Why conglomerates break themselves up

Three giant conglomerates announced their breakups in the past week. All of them are seeking to put their recent past behind them.

Why it matters: GE, Johnson & Johnson, and Toshiba weren't the last of the conglomerates. Giants both old and new remain. (Think 3M, or Softbank.) In today's financially-optimized stock market, however, the arguments for internal diversification have mostly lost the day.

Driving the news: GE is splitting into three parts; J&J is splitting into two; Toshiba is splitting into three. In each case, the newly-independent businesses are going to be a lot easier to describe than...