MARY ANN TODD, 43

FIRM: Munger Tolles & Olson LLP

LAW SCHOOL: Yale

CLIENTS: Berkshire Hathaway Inc., Universal Music Group, 99 Cents Only Stores

When Berkshire Hathaway is one of your major clients, you have to be ready to turn around billion-dollar deals at the drop of Warren Buffett’s hat. Such was the case for Mary Ann Todd one week in March, when she got the call that the investment company wanted to acquire Lubrizol Corp., a Wickliffe, Ohio, maker of specialty chemicals.

As with a lot of Berkshire deals, it was a mad sprint to the finish line, with Todd participating in negotiations early in the week, and then working through the weekend to help wrap up the $9.7 billion deal by Sunday.

But that wasn’t all. On Thursday of that same week, another client, 99 Cents Only Stores, received a buyout offer from L.A. private-equity firm Leonard Green & Partners LP. (That proposal has run into shareholder opposition and still hasn’t closed.)

“I didn’t get much sleep that week, but it comes with the job,” she said with a laugh. “It’s true that when it rains, it pours.”

Todd’s firm, Munger Tolles & Olson LLP, was founded by Berkshire Hathaway Vice Chairman Charlie Munger, so she has worked on many deals for the company over the years, including its massive $34 billion acquisition of Burlington Northern Santa Fe Railway Co. in 2009 and, this August, the dramatic $5 billion investment into a teetering Bank of America. The turnaround on that latter deal was less than 24 hours.

“That was something that Mr. Buffett has said he arrived at that morning,” she said. “The quick turnaround is definitely a part of what comes with working with them.”

Other clients include Universal Music Group and Warner Music Group.

Today, she lives in Santa Monica, and spends much of her free time with a young daughter – her older daughter attends college in New York – and practicing yoga.