News Summary: Icahn raises stake in Chesapeake

THE VOCAL BILLIONAIRE: Activist investor Carl Icahn bumped up his stake in Chesapeake Energy, a company where he has already pushed for sweeping changes in governance. Icahn now owns 8.98 percent, up from a 7.6 percent stake he held this summer.

THE PUSH: Since Icahn first bought up shares in May, he's pushed for a slew of changes. Investors revolted after a series of corporate governance issues surfaced.

THE STOCK: The company lost more than half of its market value in the three months leading up to Icahn's initial investment, but shares have since increased by about 20 percent.