With dizzying speed, four long-serving magazine editors of some of the most prestigious glossies in America — Vanity Fair, Glamour, Elle and Time — said they were packing it in.

In a week, names that were the foundation of the magazine biz for years — Graydon Carter, Cindi Leive, Robbie Myers and Nancy Gibbs, a total of 62 years as top editors — were history.

“The days of the celebrity editor are over,” said Reed Phillips, an investment banker at Oaklins DeSilva+Phillips, surveying the incredible fallout.

“I can’t recall this ever happening before,” said Peter Kreisky, an industry consultant. “It’s amazing and quite troubling to see four crème de la crème editors exit while still clearly at the top of their games. It sends a startling message about the industry’s future.”

Carter, Vanity Fair’s editor-in-chief, kicked off the rush to the exits on Sept. 7, when he told staffers that he was going to be exiting his job at the Condé Nast title by year end. He angered top brass by giving his exit interview to the New York Times a day before he told them he was announcing his retirement.

On Thursday, Leive at Glamour told her staffers she was exiting her job at the glossy, also by Dec. 31, after a 16-year run.

In between, Myers, 17 years atop Elle, told her shocked staffers on Sept. 11 that she was leaving almost immediately. She is out Friday.

Myers’ replacement, former Marie Claire creative director Nina Garcia starts Monday — leaving Myers, what, a weekend to clear out a decade and a half of memories.

Gibbs’ departure was even swifter. As rumors began to circulate, she made the announcement on Tuesday night — shortly after hosting a panel discussion in the Time Inc. auditorium — that she was exiting Time after 32 years, including four in the editor-in-chief slot.

Ed Felsenthal, the company’s top digital editor, was named as her replacement on Thursday. Gibbs will stick around as editorial director of the Time News Group to help in the transition.

So what’s going on?

Well, for one, it is planning time for all the big publishers and, with big budgets cuts said to be looming at nearly every company, heads are likely to roll. For some editors, the face in the mirror had a bull’s-eye on it.

Said one former top executive, “It’s hunting season — but that’s not good if you’re an endangered species.”

The celebrity editor — the ones with Town Cars, big salaries and wonderful perks — have actually slowly been disappearing for years.

Three top editors at Time Inc. — Rich Stengel (Time), Martha Nelson (editor-in-chief of Time Inc.) and Terry McDonell (former head of the Sports Illustrated Group) all packed up and exited in recent years for one reason or another.

Even Tina Brown, a top Condé Nast editor and founder of The Daily Beast, stepped away from publishing in 2013.

“The trend is, the business has become no fun for anyone with options,” Brown told Media Ink in an e-mail.

“Facebook and Google have taken away so much of the ad revennue, editors-in-chief find most of their job today is firing colleagues they love and respect and doing three times as much with a third of the resources,” Brown added.

Faced with that pressure and the likelihood that it will continue, the 63-year old magazine veteran noted, editors quit.

Indeed. The speed at which the celebrity editors are heading to the exits is unprecedented. And the industry’s underlying problems are clearly having an impact, as the top brass try to cut costs.

“It seems to me that the folks leaving just don’t want to go through the pain of more corporate restructuring which always means less money for staff and projects while demands increase to do more,” said one magazine veteran, who counts many of the exiting editors among his friends. “My guess is that everyone has looked at the projections for 2018 and blanched.”

Hearst has not had major corporate layoffs but has been quietly pruning and consolidating at its titles.

Condé Nast went through a big restructuring in January and, according to Women’s Wear Daily, a new round is in store for the near future.

Publicly traded Time Inc. has hired McKinsey & Co., the much-dreaded management consulting firm, to help it prune $400 million in costs over the next 18 months.

Why the blood-letting?

Print revenue — from both circulation and advertising — is forecast to continue to slump over the next several years. Cuts to lower-level staff were not enough.

‘All these top cats will be replaced by top kittens, less expensive than they are.’

“Print titles will continue to lose market share as their readers continue to move to online versions of the print brands or other forms of information and entertainment entirely,” said the latest global market report from Zenith Media, which predicts magazine print ad revenues will shrink at the rate of 6 percent a year through 2019.

The report does not add magazine’s digital revenue into the mix, so it’s slightly skewed, but does show an industry under intense pressure.

But gaining a slice of the digital market is not easy — even with fairly strong digital audiences: Time Inc. has 127.3 million unique monthly visitors, Hearst nabs 104.3 million and Condé Nast digital gets 93.1 million, according to the June figures from comScore.

That’s nicely ahead of digital rivals such as Vice (72.3 million), BuzzFeed (75.1 million) and Vox (70.9 million).

But it is far behind the two digital ad behemoths: Google, with 241.4 million uniques and Facebook, with 203.9 million.

Brian Wieser, an analyst at Pivotal Research, wrote that in 2016 the two grabbed 77 percent of the gross spending on the internet — leaving the rest of the media world to battle for the remaining 23 percent.

“The future will not continue to value the skills and talents with which they have become masters of magazine media,” said Kreisky. “The game is changing faster than ever and a new generation of digital natives is taking over. Plus they face enormous pressure to cut costs to compete effectively against digital players.”

With publishing’s rising digital revenue not yet offsetting print, publishers are trying to cut costs across the board.

“All these top cats will be replaced by top kittens, less expensive than they are,” said a magazine veteran.

And it’s easy to see why.

Carter was said to have a package of about $2 million a year, and Leive was estimated to be in the $1.25 million range.

They may be better protected than most as they exit because, sources said, they landed their Condé Nast jobs when there were still good long-term retirement benefits. The two could collect in retirement up to 50 percent of their salaries, sources said.

Younger editors were not accorded that perk.

Gibbs was estimated to be earning somewhat less than the $700,000 base and $289,000 bonus that predecessor Rick Stengel disclosed as his compensation for his last year on the job in 2012 — before heading to the State Department under President Obama.

But Gibbs was still estimated to be pulling in a high six-figure salary in the range of $850,000 — and if Time’s stock ever revives, she could cash in stock options.

Hearst was always known to pay somewhat less than Condé. Sources estimate that Myers’ bonus and base on the Hearst title has her in the $1 million range.

But hard reality will likely leads to more cuts. And none may be more vulnerable than the seven-figure salary of top editors.

“Magazines are no longer the profit centers they once were with margins of 20 to 30 percent,” said Phillips. “There is certainly a risk in removing proven editors, but media owners have decided the economics of their businesses cannot survive in the long term without trimming costs.

Phillips predicts more top editors are likely to exit in the coming months. “This is a trend that will continue.”