AT&T

CEO: Randall Stephenson

Dec. 30, 2016: $42.53

June 30, 2017: $37.73

Change: -11.29%

During the first half of 2017 AT&T continued taking steps to complete its $85.4 billion acquisition of global entertainment and media powerhouse Time Warner, which was announced in October 2016. The acquisition, which AT&T hopes to close this year, is part of a broader trend among telecommunications carriers to add content to their offerings.

In June AT&T struck a deal to acquire Brocade Communications' Vyatta Software Platform, signaling a significant shift in how the company will provide networking solutions in the future. (The acquisition closed July 7.)

For its first quarter ended March 31 AT&T reported revenue of $39.37 billion, down nearly 3 percent from $40.54 billion in last year's first quarter. Net income for the quarter was $3.57 billion, down 8 percent from $3.89 billion one year before.