During HPE’s fourth quarter earnings call, Whitman said she would relinquish the CEO title at the end of January but remain on the board. Longtime HPE (HPE) executive Antonio Neri, who had been viewed as Whitman’s likely successor after he was promoted to president in June, will become CEO Feb. 1.

Still, while Wall Street had been prepared for the succession plan, investors reacted negatively to the news. HPE stock fell more than 7% on the news in after-hours trading, despite the fact that the company reported earnings that beat analysts’ expectations.

Whitman, 61 with a multi-billion dollar net worth, is the only woman to serve as CEO of more than one Fortune 500 company. She ran eBay for a decade through 2008, then took over as CEO of Hewlett-Packard in late 2011. Two years ago, she oversaw the biggest corporate split (by revenue) in history, breaking HP and Hewlett-Packard Enterprise apart, staying on as CEO of HPE.

But when I profiled Whitman for Fortune’s Most Powerful Women issue in September, there were mounting signs that she was nearing the end of her tenure—not that she would admit it. More than five years had passed since she’d set out a five-year plan to rescue HP, and she’d accomplished many of the goals she’d outlined, though she’d emphasized there was more work to do to revive HPE’s growth.

“Given what she’s done, there’s not as many exciting things to do,” Jayson Noland, a senior research analyst at Baird, told me at the time. “It’s funny, some [investors] were concerned about Meg at the start, and now they’re concerned about who’s going to replace Meg?”

At the same time, Whitman seemed to be wavering in her commitment to HPE. Uber had publicly courted Whitman to replace Travis Kalanick as CEO, and she had entertained meetings about the job, even while denying her interest. When I asked Heidrick & Struggles, the renowned Silicon Valley headhunting firm, about Whitman’s prospects for getting another gig, it declined my request, citing its “policy of not commenting on candidates or companies engaging in a search.”

Marc Andreessen, the venture capitalist who serves on HPE’s board with Whitman, told me at the time, “Uber would have been very lucky to get her, and I’m thrilled that they didn’t.” (Andreessen is also an investor in Uber competitor Lyft.) “She’s born to run large organizations,” he added. “I think she’s happiest when she’s doing that. I don’t think she’s particularly happy when she’s not.”

Andreessen and others expect Whitman’s next move could be in politics—she unsuccessfully ran for Governor of California in 2010—though in our August interview she said, “I’m definitely not doing that.”

Here’s an excerpt from my profile of Whitman that explores the possibilities for what she might do next.

Meg Whitman licks her goggles, steps up to the ledge, places one hand on the concrete, and hurls herself, pencil-straight, into the turquoise-blue water. She’s off in a brisk freestyle crawl—“Race pace!” yells a coach—covering close to half the pool before coming up for air. It’s 7 a.m. at the outdoor community pool in Menlo Park, Calif., where the CEO has been swimming almost every morning since January 2011—just after she lost the race for California governor, just a few months before she took over Hewlett-Packard at the darkest point in its history. She’s not just doing laps; it’s a “boot camp–ish” routine of breaststrokes and freestyle sprints and flip turns, and Whitman, in lane six of the 10-lane pool, is at the center of it all.

“I needed something to take my mind off losing,” she says of her decision to jump back in after three decades away from competitive swimming. By the time she emerges after an hour, glistening and flushed, she’s beaming; standing beside the water in a black, pool-worn one-piece bathing suit, she puts her hands on her hips and turns her face to the morning sun. It’s the ultimate power pose: This is what winning looks like.

The 61-year-old Whitman hasn’t exactly won yet. She holds a unique distinction, not just as a woman running a Fortune 500 company but as the only woman to have run more than one—first eBay, now Hewlett Packard Enterprise. (Irene Rosenfeld, the outgoing CEO at Mondelez, ran a predecessor of the same company, Kraft.) Yet today, about five years after she laid out a five-year plan to rescue HP, her success there is far from assured.

Nearly two years ago, Whitman led Hewlett-Packard through the biggest corporate breakup by revenue in history, cleaving the $103 billion company into two: HP Inc. (HPQ), where she recently stepped down as chairman, and Hewlett Packard Enterprise (HPE), where she remains CEO. At HPE, which sells servers, cloud-computing software, and “Internet of things” networking systems for businesses, Whitman has continued slicing off divisions and coaxed profits into rising. But HPE’s revenue has shrunk to an estimated $33 billion this year, and she’s not positive she can get it to grow again. Meanwhile, HP Inc., the stodgier printer- and PC-maker, has been posting near-double-digit sales growth and upstaging HPE’s stock.

“I might be the only CEO in America who wants to run a smaller company,” Whitman likes to say. But it’s not clear how much longer she’ll do that. In June she promoted Antonio Neri, head of HPE’s enterprise group, to president, positioning him as her likely successor. In August she was a top contender to replace Travis Kalanick as CEO of Uber, in which Whitman was an early investor—a job that could have teed her up to eventually lead an unprecedented third Fortune 500 company. (The ride-sharing giant went with Dara Khosrowshahi.) And recently she’s been leading on a bigger stage. A lifelong Republican, Whitman switched her support to Hillary Clinton three months before last year’s election—she was the only Fortune Most Powerful Woman to publicly campaign for a nominee—stoking speculation that the former gubernatorial candidate would reenter the political arena. “Frankly, I think a leader of every organization now needs to stand up and be counted,” Whitman says. “History will judge.”

Whitman is still most celebrated for her decade at eBay, which she grew from oddball dotcom startup to e-commerce powerhouse. But the reputation she earned there is the opposite of who she’s become: a turnaround CEO, the grownup who could clean up HP’s mess—and why not Uber’s too? The cynic’s view is that she’s a one-hit wonder, boxed in at a company whose glory days are long behind it. Now, confidants think the intensely competitive Whitman wants another chance to solidify her legacy. Says Neri, “Meg does not like to lose, trust me; she does not like to lose.”

For the rest of the story, read “HPE’s Meg Whitman Won’t Be Uber’s CEO. But She Could Be the First Female President,” from Fortune’s Oct. 1 issue.