99 percent of the S&P 500 index’s gains for the year
In the first half of 2018, as stock market indexes (especially the tech-heavy NASDAQ) blew through historical highs, a total of six companies, all usually lumped in the category of the “tech”—or, more broadly, the “Internet”—sector, generated a full 99 percent of the S&P 500 index’s gains for the y…