stocks

Bloomberg compiled S & P data
Bloomberg

Amid coal bankruptcies, increasingly cost-efficient oil and gas companies, and a trade war underway, the energy sector has dropped to its lowest share of the S & P 500 in a long time. S & P 500 is an index of major companies that represent the U.S. stock market.

Cloud Peak Energy's share price over the course of a year
Seeking Alpha

The coal company Cloud Peak Energy filed a stockholder rights plan, more commonly known as a poison pill provision, with the Securities and Exchange Commission this week. It's a way of protecting management from a hostile takeover from a new investor.