The announcement last week that Starbucks chief operating officer Roz Brewer would become CEO of Walgreens Boots Alliance in mid-March was met with enthusiasm on Wall Street because a massive company was getting a widely admired executive as its CEO. But there was also widespread elation that a new Black CEO would be joining the ranks of those on the Fortune 500, and a woman no less, an all too rare occurrence.

But at the end of March, the meager ranks of Black leaders atop America’s largest corporations will thin again after Roger Ferguson Jr., steps down as chief executive of pension fund TIAA after almost 13 years.

That will leave only four Black CEOs on the Fortune 500: Brewer, Ken Frazier at Merck, Marvin Ellison at Lowe’s, and René Jones at M&T Bank. The all-time high was six in 2012. Which prompts the question: Why, after so many years of awareness of this problem, is that number still so stubbornly low?

In the history of the Fortune 500 list, first published in 1955, there have been only 19 Black CEOs out of 1,800 chiefs. Clifton Wharton became the first Black CEO ever of a major U.S. corporation when he took the reins of TIAA in 1987, but at the time, the company was included on a service companies list, separate from the main Fortune 500 list despite its large size.

The picture gets grimmer if you take out interim CEOs or any chief who spent less than a year in the corner office: only 15 chief executives, a paltry figure when you consider Black people make up one-eighth of the U.S. population.

More worrisome, observers and executives agree, is that there is no quick fix, given the years it takes to groom someone for the C-suite. A major source of the problem is that too few Black businesspeople are put on a management track early in their career, in which a promising executive is given oversight of a business with its own profit and loss (P&L) benchmarks, the measures by which superiors and the board assess whether someone is CEO material.

“The tracks that lead to the CEO jobs are primarily P&Ls,” says Michael Hyter, chief diversity officer at consulting firm Korn Ferry. “There are a lot of people of color in support roles [accounting, marketing]—lots. That’s not what gets you into the CEO job.”

Take an executive like Lowe’s CEO Marvin Ellison, who previously led J.C. Penney, making him the only Black CEO to lead two different Fortune 500 companies. He started his retail career in loss prevention at Target. But at Home Depot, where he spent many years, he jumped to store management, giving him a P&L by which to measure him as he rose up. He was passed over in 2014 when Home Depot changed CEOs, and he went to Penney.

There are plenty of other factors at play, such as the schools from which big corporations recruit, which too often include primarily traditionally elite schools. M&T Bank, under René Jones, has made a greater effort to recruit from a broader range of schools to remedy that.

Yet Jones says helping people make their way up large established companies is only part of the solution. As much as leading a Fortune 500 is the holy grail for countless business school students, young Black entrepreneurs could be the ones building the Fortune 500 companies of tomorrow and beefing up the tally that way.

“We too often look to the Fortune 500 largest companies when, in fact, it’s logical that the next leaders today sit outside the Fortune 500,” says Jones, who’s headed M&T, a Buffalo-based bank, for three years. “It’s our job to seek them out and help mentor them to the next phase.”

In the meantime, there are lessons such entrepreneurs and strivers can learn from the only 19 Black CEOs in the history of the Fortune 500.

Despite the small sample size, their experiences mirror those of the broader chief executive population: Three were interim CEOs (Mary Winston at Bed Bath & Beyond; Derica Rice at Eli Lilly, James Bell at Boeing); three clashed with boards and top shareholders over strategy (Sears’ Aylwin Lewis, Maytag’s Lloyd Ward, and McDonald’s Donald Thompson); one was ousted by activist investors (Darden Restaurants’ Clarence Otis Jr.); one left amid allegations of accounting irregularities (Fannie Mae’s Franklin Raines); one was pushed out as his firm began to implode (Merrill Lynch’s Stan O’Neal); and one amid a personal conduct scandal (Tapestry’s Jide Zeitlin).

On the brighter side, American Express’s Ken Chenault, Delphi Automotive’s Rodney O’Neal, TIAA’s Ferguson, Xerox’s Ursula Burns, Merck’s Ken Frazier, Aetna’s Ronald Williams, and Time Warner’s Richard Parsons have had storied careers, celebrated beyond their industries. And under Jones, M&T Bank has grown, while Ellison’s tenure at Lowe’s has proved far more successful than his time at J.C. Penney.

Whatever awaits future Black CEOs, additions to the Fortune 500 could be few and far between if corporate America doesn’t move to fill its pipeline of Black talent. On the encouraging side, that is becoming much more of a priority since last summer’s social unrest over racial inequality, says Korn Ferry’s Hyter.

“Let’s look inward at the infrastructure of how talent is developed within our organizations as opposed to being perpetually frustrated that awesome people aren’t readily available,” he says.

Current CEOs

Roger Ferguson Jr.

TIAA

April 14, 2008–present

TIAA, the financial services giant that manages $1.2 trillion in assets, has the distinction of being the only large U.S. corporation to have twice been led by a Black CEO. (One of Ferguson’s forebears, Clifton Wharton, was CEO from 1987 to 1993, but the company was not included on the Fortune 500 at the time, because the list was focused on industrial companies back then.)

When Ferguson steps down in late March after 13 years, he will have done so leaving a mark on TIAA and corporate America broadly. Before joining TIAA in 2008, the Harvard-educated lawyer had a long career in public service, notably helping coordinate the Federal Reserve’s response to 9/11. He later steered TIAA through the 2008–09 financial crisis.

Ferguson has been an active proponent of Black CEOs speaking out against racism, telling Fortune last year that he has been mistaken for a waiter at business events in the past. His directorships include seats on the boards of Alphabet and General Mills, as well as the Smithsonian Institution.

Kenneth Frazier

Merck

Jan. 1, 2011–present

Though not an especially political person, Frazier made headlines in 2017 when he abruptly withdrew from former President Trump’s American Manufacturing Council after the latter made comments about a deadly white power march in Charlottesville, Va., seen as sympathetic to white nationalists. Others followed Frazier’s lead, resulting in the council’s disbanding. Frazier, leading one of the country’s largest drugmakers at a time Trump was talking about lowering prices on pharmaceuticals, has said it wasn’t about politics so much as defending basic American values.

In December, he helped found a group of CEOs from 37 major employers, including IBM, Nike, Target, Delta Air Lines, and Merck, pledging to hire 1 million Black workers in the next decade.

At Merck, the Harvard Law School–trained Frazier has helped the drug giant refocus itself on research and development, particularly early stage research. His decades-long career at Merck has included time as its general counsel, during which he robustly defended the company against litigation stemming from the recall of painkiller Vioxx. He sits on a number of boards, including that of Exxon Mobil.

Marvin Ellison

First J.C. Penney, now Lowe’s

J.C. Penney: 2015–18, Lowe’s: July 2, 2018–present

Ellison holds the distinction of being the only Black CEO to helm two Fortune 500 companies, both retailers: the first, department store company J.C. Penney, the second, home improvement giant Lowe’s.

He grew up in tiny Brownsville, Tenn., in poverty, as one of seven children. His parents struggled, but twice a year, they would shop at J.C. Penney, giving him a taste for retail. His career in the industry started almost by accident. To help pay for books and rent in college, he took a part-time job as a security officer at Target, a gig that turned into 15 years, as he climbed the ranks in theft prevention. In 2002, he moved to Home Depot, where made his way to head of U.S. stores.

But in 2014 he didn't get the CEO job and he went to J.C. Penney, which was dealing with a life or death crisis. As president at Penney, Ellison was groomed to fill the CEO role the following year. Once he took the reins, he made big moves to repair the severely damaged retailer. But the improvements only went so far under the weight of so much decay. (Penney filed for bankruptcy protection last year and is a much smaller chain now.) Ellison left for Lowe’s, where he is leading a convincing turnaround of the home improvement chain and helping it be more competitive with bigger rival Home Depot.

René Jones

M&T Bank

Dec. 20, 2017–present

Courtesy of M&T Bank

Until the George Floyd killing and resulting nationwide unrest last year, René Jones was not a particularly outspoken CEO on social issues. But the chief of Buffalo-based M&T Bank has become vocal about the need for large employers like his to diversify the pool of job candidates. M&T has moved further in that direction by shifting more of its college recruitment to historically black colleges and universities.

Jones, the son of a Black World War II vet and the woman he met in Europe, has been at M&T since 1992 and was named CEO three years ago. As CEO he is making workforce diversity a bigger priority. A CPA by training, Jones is also ramping up efforts to hire more from Buffalo’s local talent pool.

Veterans, in reverse chronological order of departure

Jide Zeitlin

Tapestry

Sept. 4, 2019–July 20, 2020

When Zeitlin was appointed CEO of the parent company of Coach and Kate Spade in 2019, his mandate was clear: help Tapestry re-energize its flagship Coach brand and finally turn around the Kate Spade label, whose acquisition by Tapestry in 2017 by his predecessor, who exited abruptly, has led to large write-downs.

Zeitlin had been chairman of the Fortune 500 company since 2014 and therefore intimately familiar with the company and the retail industry. While he didn’t have much sector-specific executive experience before becoming Tapestry CEO, he was a well-regarded businessperson; he had spent 19 years at Goldman Sachs earlier in his career. The Harvard MBA had a compelling personal background too: As a new graduate in the 1980s, he worked in apartheid South Africa to help labor groups assist black miners and witnessed firsthand how black aspirations were crushed systematically.

A few weeks before his abrupt departure from Tapestry last summer, Zeitlin wrote forcefully in a LinkedIn post of how the killing of George Floyd had affected him and said succinctly, “Black Lives Matter.” But in July, he left the company after its board opened an investigation into his personal behavior as a result of a woman alleging that he had posed as a photographer in 2007 to lure her into a romantic relationship.

Kenneth Chenault

American Express

Jan. 1, 2001–Feb. 1, 2018

Chenault’s 17-year stint atop the financial giant gives him the honor of having the longest CEO tenure ever of any Black CEO. He joined AmEx in 1981, working in strategic planning and making his way up the ranks. Before becoming CEO, selected by his predecessor, Harvey Golub, Chenault had been operations chief.

He is widely credited with having built one of the biggest loyalty programs in the world. His A-list fans include Warren Buffett, whose Berkshire Hathaway was American Express’s largest shareholder when Chenault retired; Buffett went on to name Chenault to the Berkshire board, replacing Bill Gates last year. Earlier in his career, Harvard Law School alumnus Chenault worked at Bain & Co., where he was mentored by Mitt Romney.

In one of his biggest tests as CEO, Chenault led his company out of the crisis that followed 9/11: American Express had thousands of workers in the towers next to the World Trade Center. His business savvy is now sought after by younger companies, landing him on the board of Airbnb. He also became managing director of venture capital firm General Catalyst last year and is a board member on the Council of Foreign Relations.

Ursula Burns

Xerox Holdings

July 1, 2009–Jan. 1, 2017

As CEO of Xerox, Burns was the first and one of only two Black women to ever run a Fortune 500 company. (Roz Brewer becomes the third on March 15 when she takes the reins at Walgreens Boots Alliance.) The executive’s own career at the print and digital services business began with a 1980 internship, culminating in her eventual titles of president in 2007, chief executive in 2009, and chairman in 2010. Burns led Xerox through a tumultuous period, starting with the $6.4 billion acquisition of Affiliated Computer Services in 2009 and ending with the 2016 separation of the business into two companies: document technology company Xerox Corp. and business process outsourcing company Conduent.

After stepping down as CEO following the company’s split in two, Burns stayed on for a short time as chairman of Xerox Corp. She followed up her Fortune 500 tenure with a stint as CEO and chair of the telecommunications business Veon. Burns departed that role in mid-2020 and in the months since has become an even more outspoken voice for racial justice and support for Black employees in corporate America. Burns now serves on the boards of Exxon Mobil, the Ford Foundation, IHS Towers, Nestlé, Uber, and Waystar.

Don Thompson

McDonald’s

July 1, 2012–March 1, 2015

Don Thompson worked at McDonald’s for 22 years before ascending to the top job in July 2012. In his previous roles as head of U.S. business and then operations chief, he’d been part of an incredible run at the Golden Arches: eight years of consecutive same-store sales growth, a nearly 50% increase in revenue, and a more than doubling of profits.

Just as Thompson’s tenure began, cracks started to appear in the company’s performance as it faced fierce competition, a restaurant industry that was stagnant overall, and a struggling lower-income consumer.

Thompson undertook numerous efforts to try to revitalize the company—shaking up the management team, investing in digital endeavors, customization through a build your-own-burger platform, new marketing, and both simplifying and localizing the menu.

But the period ended up being a historically abysmal time for McDonald’s. In 2014, for the first time since 2002, the company reported a global decline in sales at outlets open for at least a year. And for the first time in at least 30 years, sales declined in the U.S. business.

Thompson asked for more time to turn the company around, but in January 2015 McDonald’s announced he was stepping down after two and a half years at the helm. Thompson went on to found Chicago-based venture capital firm Cleveland Avenue, which specializes in food and beverage businesses, and sits on the boards of alternative meat startup Beyond Meat, financial services company Northern Trust, and Royal Caribbean Cruises.

Rodney O’Neal

Delphi Automotive

Jan. 1, 2007–March 1, 2015

Spending eight years at the helm of car parts giant Delphi made O’Neal the most prominent Black person in the car industry during an era of intense change for the sector. He took the helm of the company about halfway through a massive restructuring in federal bankruptcy court but left Delphi transformed and prosperous.

Delphi was originally spun off from General Motors and was heavily reliant on the carmaker for its sales. By the time O’Neal was done with Delphi as CEO, the company got about 18% of sales from its former parent, compared with roughly half in the early aughts. On his watch, Delphi exited bankruptcy, returned to the stock market, and saw sales grow 45% to $17 billion in his final year. More crucially, Delphi became the dominant seller of in-car tech for things like safety and efficiency, setting it up well to serve an evolving car industry.

But his time as an executive was not without controversy: The bankruptcy left 22,000 retirees with lower benefits.

Clarence Otis Jr.

Darden Restaurants

Nov. 29, 2004–Oct. 14, 2014

Otis led the owner of Olive Garden, Capital Grille and LongHorn Steakhouse for nearly a decade, which was marked by fast growth for the most part. But in the last two years of his stint, he was unable to quell market share losses as consumers started flocking to cheaper options such as Panera and Chipotle.

That put Otis and the company in the crosshairs of activist shareholders calling for change, some going so far as to suggest how Olive Garden should prepare its iconic breadsticks. Otis sold off Red Lobster and started cost-cutting, but ultimately that did not mollify the activists, and Otis stepped down in 2014.

He had reached the corner office of a restaurant operator with an unconventional background. While restaurant CEOs typically have specific industry experience, Otis had been a securities lawyer and a manager at JPMorgan Chase before joining Darden as treasurer in 1995 and becoming CFO then CEO. He built his operational chops as president of Darden’s former Smokey Bones restaurant unit in the two years before becoming CEO.

That finance acumen has made him a sought-after director. He currently sits on the boards of Verizon, North Face parent VF Corp., and Travelers.

Ronald Williams

Aetna

Feb. 14, 2006–Nov. 29, 2010

Even though Ron Williams left Aetna more than a decade ago, his impact on the health care industry can still be felt: As CEO, he played a critical role in shaping former President Barack Obama’s Affordable Care Act, a.k.a. Obamacare.

His lasting influence stems from other sources too. As a sought-after ex-CEO, Williams’s firm, RW2 Enterprises, advises C-suite leaders on strategy development and how to get employees on board with where a CEO is heading. He has built a highly successful post-CEO career: On top of being chairman of the Conference Board’s board of trustees, he is on the boards of American Express, Boeing, and Johnson & Johnson.

On his watch, Aetna (part of CVS Health since 2018) revenues nearly doubled, having turned around a struggling insurer. The Chicago-reared son of a bus driver and a manicurist told Fortune in 2019 that he was “the least likely person ever to lead a $34 billion corporation.”

Aylwin Lewis

Sears Holdings

Oct. 18, 2004–Feb. 18, 2008

Lewis was tasked in late 2004 with retail’s mission impossible: making sure that the union of Kmart, which he’d led for over a year at that point, and Sears revitalized both iconic but struggling retailers.

The merger was the brainchild of hedge fund manager Eddie Lampert, who hoped that their expansive store fleets, economies of scale, and complementary product assortments would form an industry-leading company. But Lewis, who was ousted in early 2008, never stood a chance. Overruling his CEO, Lampert focused on cost-cutting rather than on improving stores, even as Target and Walmart started to poach Sears’ lower-income shoppers.

History ultimately proved Lewis and some of his successors right: Sears filed for bankruptcy protection in 2018, while Lewis in 2008 became CEO of a much smaller but more successful company: Potbelly, which he led until 2017. His board directorships have included Marriott and Walt Disney.

Richard Parsons

AOL Time Warner

May 16, 2002–Jan. 1, 2008

When Parsons became CEO of Time Warner, the drama-free banker (he had been CEO of Dime Bancorp in the 1990s) and lawyer was a breath of fresh air in an industry known for its flamboyant, hard-charging CEOs. And his approach worked. Business units at Time Warner, which had merged with America Online and experienced fractious relations, learned to work harmoniously with one another under Parsons.

He slashed the company’s debt with headline-grabbing moves, like selling the Warner Music division. Parsons retired in 2008 and has had plenty to keep him busy. His dealmaking acumen landed him a role as senior adviser to private equity firm Providence Equity Partners, and he cofounded Imagination Capital, a venture capital firm. When CBS was embroiled in a crisis in 2018 that forced Les Moonves out as CEO amid allegations of sexual harassment and assault, Parsons was brought in to steady the company. But he left after only a month because of illness.

Parsons, who had spent 16 years as a director at Citi through 2012, including four as chairman, sits on the boards of investment bank Lazard and Madison Square Garden. But Parsons, a man about town at New York’s countless cultural events, also lends his talents to a number of arts organizations including the Apollo Theater Foundation and the Jazz Foundation of America.

Stan O’Neal

Merrill Lynch

July 23, 2002–Dec. 31, 2007

O’Neal made finance history when he became the first Black CEO of a Wall Street firm in 2002. Alas, though he was named Fortune’s most powerful black executive in America that year, his tenure did not end well; he was forced out five years later as Merrill Lynch began to implode. To transform Merrill Lynch from a stodgy brokerage into a fast-growing company, he got the firm to embrace riskier activities such as outsize exposure to subprime mortgage assets and to de-emphasize its bread-and-butter stocks and bonds trading, eschewing the company’s “Mother Merrill” culture, so-called because of the firm’s quasi-parental, nurturing approach with clients and job security for staff.

While that worked initially, turning Merrill into the top brokerage, it sowed the seeds of disaster later on. By 2007, Merrill had dealt with an exodus of top staff who didn’t care for the new culture, and the company had to write down $8 billion worth of assets during the subprime mortgage crisis. He was ousted that year, but his successor couldn’t undo the damage, and Merrill was ultimately bought by Bank of America in 2009 during the financial crisis.

O’Neal, who had started his career at General Motors in financial roles, joined Merrill in 1986. After Merrill, he never landed another C-suite job. But he has served on some boards and is currently a director at aluminum products maker Arconic.

Franklin Raines

Fannie Mae

Jan. 1, 1999–Dec. 22, 2004

Raines became the first Black CEO of a Fortune 500 company in 1999, but unfortunately his history-making tenure ended in turmoil. He resigned from Fannie Mae, formally known as the Federal National Mortgage Association, under pressure in 2004 after revelations of extensive accounting irregularities. The allegations dogged him for years after he left the mortgage finance company, but in 2012, Raines was dropped from a class action suit by investors, accusing him and others of deceiving them. His once stellar career never quite recovered.

The Harvard Law grad and Rhodes Scholar had long bounced between public service and corporate life. After college, he worked for Presidents Nixon and Carter in economic posts in the 1970s. In the following decade, he worked at New York investment bank Lazard Frères, specializing in municipal finance. In 1991, he went to work for Fannie Mae. Five years later, he returned to working for a President, becoming a cabinet member in Bill Clinton’s administration as head of the Office of Management and Budget in 1996. And in 1998, he rejoined Fannie Mae, quickly ascending to the top job.

Alas, Fannie Mae ended up being seen as a major cause of the subprime mortgage crisis, and he kept a lower professional profile after his departure, though he has stayed active as a venture capitalist and is on the board of regents of the Smithsonian Institution.

Lloyd D. Ward

Maytag

Aug. 1, 1999–Nov. 1, 2000

Ward enjoyed a short stint as CEO of Maytag, spending all of 15 months leading the appliance maker before leaving in the wake of a disagreement with its board over strategy. He had ascended to the corner suite after only three years at Maytag and won kudos for the pace of new product introductions on his watch, notably with higher-end appliances. But the company struggled as rivals undercut Maytag prices on the lower end.

Still, Ward rebounded, going on to a high-profile role: A year after his exit from Maytag, he was named chief executive of the U.S. Olympic Committee as it scrambled to get ready for the 2002 Salt Lake City Winter Games. But he was ousted and stripped of a bonus the following year because of an ethics violation that also cost him his seat on the JPMorgan board.

Before Maytag, he had been a senior executive at big consumer companies such as PepsiCo’s Frito Lay division and Procter & Gamble. Ward is still active, partaking in Wall Street’s investment structure du jour: blank check companies. A special purpose acquisition company (SPAC) he cofounded in 2016 bought a car parts firm in the fall of 2020.

Former interim CEOs

Mary Winston

Bed Bath & Beyond

May 13, 2019–Nov. 4, 2019

Winston, an executive with extensive finance and accounting experience, was only the second Black woman to ever land on the Fortune 500 as CEO, doing so on an interim basis two years ago at Bed Bath & Beyond. Her predecessor had been ousted abruptly as the struggling home goods retailer faced an activist investor pushing for a major overhaul.

While interim CEOs often land the job permanently, Bed Bath & Beyond ultimately poached Target’s former chief merchant to be its new chief executive. Winston, who remains on the company’s board as it executes its turnaround, had previously served as CFO of Family Dollar until it was bought by Dollar Tree six years ago, and before that, filled the same role at grocer Giant Eagle. She is now the president of her own consulting firm, WinsCo Enterprises, and serves on the board of Chipotle Mexican Grill.

Derica Rice

Eli Lilly

May 1, 2013–July 1, 2013

Rice’s stint as CEO is the shortest in this cohort, but that was by design. The CFO at pharma giant Eli Lilly stepped into the CEO role on an interim basis while his boss, John Lechleiter, was out on medical leave to deal with a dilated aorta. As Lechleiter’s right-hand man, Rice was crucial in helping Lilly revive sales at a tough time.

Despite the brevity of his CEO stint, Rice moved on to big roles at many of corporate America’s blue-chip companies: He left Lilly in 2018 to lead CVS Health’s massive Caremark pharmacy benefits management unit, a job he left a year ago. Rice also serves on the boards of Target, Bristol-Myers Squibb, and the Walt Disney Co.

James Bell

Boeing

March 7, 2005–June 30, 2005

Having just started as Boeing CFO a few months earlier, Bell stepped in to pinch-hit as interim CEO after Harry Stonecipher resigned in early 2005 over an affair with an underling. Stonecipher himself had returned to the company to replace a CEO who left in scandal amid ethical lapses. (A VP of finance, Bell had landed in the C-suite to replace a CFO who had left because of a government contract scandal.) The airplane maker was eager to find a chief who would fix the company and its culture and ultimately chose 3M chief Jim McNerney.

Bell’s stint as CEO was short-lived by design, and he continued to have a stellar career. After seven more years at Boeing, he retired in 2012 and has since joined the boards of bellwether corporations like JPMorgan Chase in 2011, Apple in 2015, and Dow in 2019.

Beth Kowitt and Emma Hinchliffe contributed to this project.