Ask a room of first-year MBA students where they see themselves in 20 years and a fair number will say chief executive. Far fewer could tell you how a CEO spends their week.

Nitin Nohria has spent most of his career on that gap. He taught leadership at Harvard Business School for 22 years before serving as dean from 2010 to 2020, and for 3 decades he has run the school’s New CEO Workshop, working with more than 500 newly appointed chief executives. His new book, The CEO: The Role, the Reality, the Responsibility, was published by Harvard Business Review Press on 29 September.

On LinkedIn, Nohria wrote that the ambition to hold the top job “often comes before a full appreciation of what the job actually entails,” and that his students were very much on his mind as he wrote. Knowing that busy students may not get to the book, he recorded a conversation about its central ideas with Bharat Anand, his long-time HBS colleague and, since August 2025, dean of NYU Stern.

Harvard MBAs who became Fortune 500 CEOs

HBS has a strong claim on the corner office. Fortune’s 2024 analysis of Fortune 1000 leadership counted 94 HBS MBAs in CEO, CFO and chief technology roles, and found that 6% of all Fortune 1000 CEOs hold an HBS MBA. Across the c-suite, MBAs fill close to half the top jobs.

Nohria’s deanship saw a steady run of HBS alumni take charge of Fortune 500 companies. Meg Whitman (MBA 1979) took over at Hewlett-Packard in 2011. Robert Bradway became CEO of Amgen in 2012. Mark Fields got the top job at Ford in 2014 and Darius Adamczyk at Honeywell in 2017. Larry Culp became the first outsider to run General Electric in its 126-year history in 2018, and Chris Kempczinski (MBA 1997) took over McDonald’s in 2019.

Between them, their stories cover most of what Nohria describes in the book, including the parts students tend to skip.

How much does a CEO affect company performance?

When Nohria became dean, people told him the 100-year-old school would outlast him whatever he did. Investors say much the same about Microsoft or Procter & Gamble: strong brands, strong market positions, put anyone in charge.

Nohria, Anand and Noam Wasserman studied how much of a company’s performance can be traced to its chief executive. Their answer, Nohria tells Anand, is roughly 15% of the variance over an extended period. Industry, he points out, explains about the same share. “Every choice of the CEO is the same as a board deciding we should switch from pharmaceuticals to cement,” he says.

Mark Fields shows how quickly that can go wrong. Ford’s market value fell by close to 40% during his 3 years in charge, and the board replaced him in May 2017 despite strong truck and SUV sales. Nohria is blunt about the deal: “If you don’t deliver results, the rope in the end breaks.”

How CEOs spend their time, and why customers get 3%

New CEOs at the workshop consistently ranked managing their time as the thing they felt least prepared for. So Nohria and Michael Porter measured it. They tracked 27 CEOs, around the clock, for a quarter each, building up 60,000 hours of data, and published the results, “How CEOs Manage Time” in Harvard Business Review in 2018.

The CEOs worked on 79% of weekend days and 70% of holiday days. The number they argued with hardest was time with customers, which Nohria puts at about 3%. “Go back and check. This must be wrong,” several told the researchers. The data came from their own calendars, coded by their own assistants. Customers rarely ask for the CEO’s time, so they rarely get it.

Oriana Bandiera of LSE, with Andrea Prat of Columbia, Stephen Hansen and HBS’s Raffaella Sadun, took diary research to 1,114 CEOs in 6 countries. Published in The Journal of Political Economy in 2020), they found 2 broad types: “leaders”, who spend time in high-level meetings across several functions, and “managers”, who hold one-to-ones with core functions such as production. Firms run by leaders did better on average, though much of the gap came from a poor fit between CEO and firm. A new CEO took around 3 years to show up in the numbers.

Nohria’s advice on meetings is pleasingly practical. Microsoft Outlook, he jokes, has more influence over meeting length than the people booking them, which is why hour and half-hour slots dominate. Setting the length deliberately “will save you 25, 30% of your time.” He also asks leaders to decide what each person should feel, know and do when they walk out of the room.

Setting priorities means saying no

Every CEO has priorities, Nohria says, yet staff often can’t name them, because it’s easier to give everyone a little time, a little money or one new hire. “The real measure of priorities is when you have the courage to say no.” As dean he had his “five I’s”: innovation in education, intellectual ambition, internationalisation, inclusion and integration with the wider university. Colleagues joked that he talked about nothing else, which was the point.

He applies Porter’s view of strategy to speech. A CEO has no casual conversations; every remark is read as a signal, and some old friends found him less available once he became dean. What you choose not to say matters as much as what you say.

The jerk, the saint and company culture

Nohria argues that a CEO’s most important decisions are about people. He uses the HBS case of Rob Parsons, a Morgan Stanley banker who delivers excellent numbers while frightening colleagues and bending the rules. Every CEO, he says, recognises their own Rob Parsons. Most admit that when they finally let that person go, the damage they feared didn’t happen and the rest of the organisation gave “a giant exhale”.

The harder call is the “saint”: the loyal, well-liked colleague who has lost a step. Organisations mourn saints. Moving them on still matters, he says, because tolerating underperformance tells everyone what the culture will accept.

Kempczinski took over at McDonald’s after the board dismissed his predecessor, Steve Easterbrook, for a relationship with an employee, and set about building a more professional culture. Nohria’s view is that a CEO sets culture through decisions about who stays, who goes and who gets promoted.

Are MBA-educated CEOs more short-termist?

Students who want the job should also read Danny Miller of HEC Montréal and Xiaowei Xu of the University of Rhode Island. In a 2019 Journal of Business Ethics study of large US public companies, they found MBA-educated CEOs were more likely than their non-MBA peers to manage earnings upwards and cut R&D, and that market valuations suffered afterwards.

Nohria quotes Warren Buffett, who told staff at Salomon Brothers to stop trying to win by playing close to the lines. The best CEOs, Nohria argues, win the ordinary points in the middle of the court, every day. Results keep a CEO in the job. Legitimacy, which he defines as people actively wanting to be led by you, comes from being seen as fair, human and authentic. The thing he values most from his decade as dean is that the gardeners and dining room staff at HBS still give him their biggest smile.

How long should a CEO stay in the job?

Asked what CEOs most reliably fail at, Nohria says leaving gracefully. In what he calls a crude analysis of every CEO he knew who had served 8 years or more, company performance was on average worse in the second half of their tenure. He borrows a rule from Bill George, the former Medtronic CEO who later joined the HBS faculty: 10 years, plus or minus 2. “Leave when people ask the question, ‘Why are you leaving so early?'”

Research from Temple University’s Fox School points the same way. Xueming Luo, Vamsi Kanuri and Michelle Andrews studied 365 US firms between 2000 and 2010 and the results published in Strategic Management Journal estimated the optimal CEO tenure at 4.8 years, against an average of 7.6. The longer CEOs stayed, the closer they grew to employees and the more distant from customers.

Some of the Nohria-era appointments are now old enough to face the question. Bradway has led Amgen since 2012. Culp, who ran Danaher for 13 years before GE, has a contract at GE Aerospace that runs to 2027. Their boards will judge them on more than a rule of thumb.

Nohria’s advice for MBA students who want to be CEO

For the MBA student with a CEO plan, Nohria’s core lesson is that the job runs on indirect influence. “You don’t make all the decisions, but you have to shape the conditions that allow others to make the best decisions.”

He also offers a test that works long before anyone hands you the top job. If a week passes without hearing something that makes you wince, people have stopped telling you the truth.

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