To her friends in college, Hobson seemed like a normal kid. But she was preternaturally aware. In a letter to her sister Pat at the start of freshman year, she talked about her “incredible day” spent volunteering at a Princeton nursing home. “It really made me think about how scary it is to age, (especially for mommie) and how unfair we as Americans are to the people who raised us and who have practically built this country by hand,” she wrote. She added, “Talking with the elderly also does wonders for my communication skills.” And she wrote this to her sister, who had helped raise her. “Although I don’t have much (yet) what I do have is yours.”

After college, she returned to Ariel, where she had done a summer internship. “I was desperate to understand money, desperate for financial security,” says Hobson. “I felt like financial security would be the biggest gift I could ever have, ever.” She became an unofficial chief of staff to Rogers, a role in which she’d challenge herself by seeing if she could anticipate his answer—and then by seeing if she had a better one. In 2000, Rogers, who oversees the investing side of the business, named her president. She hustled. Laurence Kandel, a vice president at Obermeyer Asset Management in Colorado, says he’d see her on the sales circuit, drumming up business. “She’s at things I wouldn’t expect, things where she is by far the most senior person in the room, and she’s there doing the hand-to-hand combat,” he says.

Hobson also became both politically and philanthropically engaged at a remarkably early age. In the mid-1990s, she and Rogers founded Ariel Community Academy, a public school on the South Side of Chicago that includes course work on financial literacy. In 2002, Ariel launched the Black Corporate Directors Conference to bring together board members from Fortune 500 companies. Hobson was an early supporter of Barack Obama’s, and in 2000 she helped with Bradley’s presidential run. “Even when Mellody was really young, people would say, ‘I see this woman everywhere,’ ” says Peter Thompson, whose aunt Maggie Daley also became close to Hobson. “She started cracking this scene early on.”

The Bradley campaign also helped Hobson formulate her life’s motto. She remembers a fund-raising trip to St. Louis with Louis Susman, the former U.S. ambassador to the U.K. “I said, ‘Lou, what do you want?’ He said, ‘I want to have an interesting life and be surrounded by good people.’ I said, ‘That’s it.’ I added a third one, to leave the world a better place.” She says, though, that this has caused her some cognitive dissonance. “A coach at Ariel said to me, ‘Mellody, everyone doesn’t want what you want.’ This was shocking to me. It took me a long time to work through it. I thought, Not everyone wants to be around interesting people? No! Some people want to have two weeks’ vacation and to go home at five P.M.”

But it is Ariel that has been the anchor in her life. She likes to note that she’s been told she is the only person from her class at Princeton who has had the same work number since graduation. Through stock grants, as well as purchases she’s made, some by borrowing money when she was only in her 20s, Hobson has become a significant shareholder in Ariel—a stake that is worth tens of millions of dollars.

Which helps explain why the financial crisis of 2008 was such a difficult time for her. The firm had sailed through the dot-com crash, delivering above-average returns to investors, but in the 2008 financial crisis the stocks it owned were some of the hardest-hit—and Hobson had met an obstacle she couldn’t outwork. Ariel’s flagship fund fell almost 50 percent that year, and clients began pulling their money. The firm’s assets under management peaked at $21 billion in 2004 and fell to just $3.3 billion in 2009. “Every single day, clients would call and fire us,” Hobson says. “People who you’d known for years and years. It felt so personal.” She and Rogers had to lay off 20 percent of the 100-person staff. “John was asking, ‘Shouldn’t the product be better?’ ” says Hobson. “I was saying, ‘I haven’t explained it well to clients. I didn’t do a good job.’ We both owned it.”

Hobson early in her career. © Stuart Rodgers Photography.

Early one morning during the crisis, global markets were plunging. Hobson doesn’t usually focus on day-to-day fluctuations, but this day she was staring at the TV, hyperventilating. She and Lucas always talk at 7:30 A.M. Chicago time when they’re in different cities. “George said, ‘What do you know better than anyone else because you live in Chicago?’ ” she recalls. “I said, ‘George, I have no idea. I’m not interested in mind games.’ He said, ‘The one thing you have in Chicago is snowstorms. What do you know about snowstorms? In a snowstorm, when you’re trying to get from one place to another place, you never look up at the storm. You watch your feet. If you look up at the storm you will fall.’ ” Hobson says, “I went to work, and thought, We must stay focused and watch our feet. We must just do the work.”