Mary Ann Todd

For more than two decades, Todd has played a role in the growth transactions for Warren Buffet.

A corporate partner at Munger Tolles & Olson, she's been tasked with taking on mergers and acquisitions and advised on corporate governance and general strategic matters.

She was part of Berkshire's $46 billion merger of its H.J. Heinz Co. in 2015 and Kraft Foods Group. Before that, she helped Berkshire as it acquired Heinz with 3G Capital for $28 billion.

She was part of the Heinz-Kraft merger in 2015 as Berkshire Hathaway was 50 percent owner of Heinz. 3G Capital invested $10 billion in the transaction.

Last year, she represented Books-a-Million, one of the nation's largest bookstores, go private, though one of the hurdles was a legal battle between the majority and minority shareholders. The latter fought the sale in a Delaware court, arguing that the company's board of directors breached their fiduciary duties.

But the judge ruled Books-a-Million followed the framework established in a past case.

"It was rewarding in a sense that it was a great outcome for our client and shareholders, but also recognition from the Delaware court as to how it was done," Todd said.

Last fall, she also guided Berkshire through its sale of its 19.3 percent stake in Wrigley Co. to Wrigley's parent company, Mars Inc. The deal paved the way for Mars to consolidate its chocolate production with Wrigley's candy operation and the two brands formed Mars Wrigley Confectionery.

Todd said the most satisfaction from her work stems from the trust she's earned from hear clients over the years.

"Being willing to trust me with their significant transactions or need for importance advice on challenges they face ... it's the most rewarding part of my job," she said.

— Arin Mikailian