15. Abigail Johnson

Title: CEO, Fidelity

Country: US

Age: 53

In late 2014, Abigail Johnson succeeded her father Edward as CEO of Fidelity, the second-largest mutual fund company in the US, which oversees more than $5.2 trillion in assets. Johnson keeps a low profile, but it’s no secret she was groomed to take over the company from an early age. She started working at the firm in high school, and officially joined Fidelity as an analyst in 1988. Since 2012, Johnson had served as president.

Johnson wasn't slow to wield her power and effect change after assuming the top role last year, quickly moving to cut costs and fire ineffective managers. She's no stranger to power plays, reportedly maneuvering to oust her father in 2004 over a disagreement in vision (the effort failed, and Edward remains the chairman of the company).

Not only is the new Fidelity CEO responsible for millions of Americans' retirement accounts, but through her roughly 24% stake in the company, Johnson holds a personal fortune of $18.5 billion, making her one of the wealthiest women in the world.