Anchor Brewing, San Francisco’s beloved 121-year-old brewery and creator of the city’s most famous beer, is being sold to Japan’s Sapporo Holdings Ltd. in a landmark deal.

According to Keith Greggor, Anchor’s president and CEO, the move was a year in the making and the result of speaking with “many, many” larger breweries all over the world to find the right fit.

Anchor Brewing Co. is considered the leading pioneer of the craft beer movement, and is credited with reviving and modernizing some of today's most popular American beer styles. The price of the deal was not disclosed. Anchor Distilling, which produces spirits such as Junipero Gin and Old Potrero whiskey, is not involved in the deal and will become a separate company.

The news comes as the latest in a line of high-profile craft breweries purchased by larger beverage companies, following in the footsteps of Heineken’s acquisition of Lagunitas, Constellation’s 2015 takeover of Ballast Point, and AB InBev’s purchases of Goose Island and Wicked Weed, among many others.

Yet Anchor representatives said its beer would continue to be brewed at its Potrero Hill headquarters, and there would be no changes to its beer recipes. Additionally, Anchor will open a new public taproom on De Haro Street, across the street from its current brewery.

“When you take a brand like Anchor, its very soul exists in the heart of San Francisco,” Greggor said. “Of all the people we spoke to, (Sapporo) respected Anchor the most, what it stood for and the importance of its connection with San Francisco.”

Anchor Brewing has proven itself as a company of firsts. Established in 1896, it bills itself as America’s “first and oldest” craft brewery and has long been San Francisco’s homegrown pride. It weathered the 1906 earthquake and is the inventor of the California common style of beer, which it trademarked as steam beer.

But by 1965, Anchor was in dire shape and on the verge of bankruptcy when Fritz Maytag, working off a tip from an Old Spaghetti Factory bartender, bought the capsizing company for a few thousand bucks.

The most popular American beers of the era were bland, fizzy and very pale; they were cheap to make and cheap to buy. Maytag, however, didn’t see such beer as the way to salvage his new company, so instead he began making what he — and a small handful of employees — deemed good beer.

He rethought the entire brewing operation and began bottling the flagship Anchor Steam. In subsequent years, he added four beers to Anchor’s repertoire that no one else in America was making: the dry-hopped Liberty Ale, a dark porter (Anchor Porter), a barley wine (Old Foghorn Barleywine Ale) and, in a tradition that continues today, the first Anchor Christmas Ale. In 1977, he moved brewing operations to Anchor’s current Potrero Hill headquarters. Before long, the brewery was turning a profit, and set the stage for the emergence of the modern craft beer movement.

In 2010, Maytag sold Anchor to Greggor and Tony Foglio. At the time, Foglio said that the sale was “something we want to build on for the rest of our careers and pass on to the next generation.”

Yet Anchor’s new move signals a direction that is not so much trailblazing as it is increasingly conventional. It follows the trend established by many other craft breweries that have been acquired by global companies in recent years. Noting that critics also thought the idea of Maytag selling the brewery in 2010 was “heretical,” Greggor is quick to refute any potential “naysayers” surrounding the Sapporo deal.

“People bleed Anchor, they’re passionate about it,” he said. “It’s that passion that makes handcrafted beers successful in terms of its quality. Maintaining that sense in the brewery is very important, but this is something that Sapporo understands and respects.”

Anchor Brewing management said it did not specifically plan for a complete acquisition. However, to support the brewery’s long-term future and further international expansion (it currently distributes to 20 countries), it needed to relinquish full ownership to Sapporo.

The appeal of Sapporo, Greggor said, was an organization that mirrored Anchor’s values. He said that the Japanese company — founded in 1876, two decades before Anchor — understood Anchor’s commitment to keeping operations in San Francisco.

In a statement, Masaki Oga, Sapporo Holdings’ president and representative director, likened the lengthy histories of the two breweries, noting that Anchor has inspired a “new generation of brewers and beer lovers around the world.”

So what does the deal mean for the San Francisco brewery’s future?

Greggor said that Anchor’s main sticking point in the deal was to continue using the Potrero Hill brew house — at least for the time being.

”Sapporo committed to investing in the Potrero Hill brewery until we exceed capacity of that brewery, but I have no idea when that would be,” Greggor said. “We are currently running at about 55 to 60 percent of that capacity.”

However, the deal also likely means that Anchor’s long-delayed Pier 48 expansion is more likely to be dead in the water, though Anchor would not comment on the status of the project.

The company will update its production systems and its packaging process. “We have a rather inefficient canning system,” he said. “They would invest in much better canning equipment. We have a rather difficult, labor-intensive management of our glass (bottles). Automatic palletizing, things like that, will be looked at.”

When asked whether this deal jeopardizes Anchor’s “craft” designation, a commonly accepted definition dictated by the Brewers Association, the brewery’s executives did not seem concerned about that imminent debate, due to the brewery’s long history.

“Anchor has been making handcrafted beer since long before ‘craft’ was coined,” Greggor said. “I would argue (Anchor’s beer) is more handcrafted than any of the craft beer out there today. However, while it might not fit the definition of some self-appointed organizations, we’ll always be the original, and we’ll still be handcrafted in San Francisco.”

Alyssa Pereira is a pop culture and beer reporter at SFGate and The San Francisco Chronicle. Email: apereira@sfchronicle.com Twitter: @alyspereira