Marriott International can finally breathe a collective sigh of relief, having officially purchased its former rival, Starwood Hotels & Resorts, for roughly $13 billion, nearly a year after the deal was first announced last November.

According to the terms of the deal, Starwood’s shareholders receive $21 and 0.8 shares of Marriott for each share of Starwood stock. With Marriott’s stock closing on Sept. 22 at $69.75 per share, that amounts to $76.80 per share of Starwood.

The CEO of Marriott, the former CEO of Starwood, and More Are Speaking at Skift Global Forum 2016. Join Us.

And to mark the creation of the world’s largest hotel operator, with 30 brands and more than 1.1 million rooms in more than 5,700 hotels in 110 countries worldwide, Marriott has announced some big news related to its loyalty program.

Beginning today, members of both Marriott Rewards and Starwood Preferred Guest (SPG) can now link their accounts, something not often announced when travel companies of this size come together. The linking of the two programs includes immediate status matching and point transfers and redemptions whereby three Marriott Rewards points are equivalent to one Starpoint.

It’s not quite a complete integration: Both programs are still, technically, two different programs (three if you include The Ritz-Carlton Rewards, which is part of Marriott Rewards), and the programs most likely won’t be fully combined until 2018.

To earn points with Marriott, you still need a Marriott Rewards account, and vice versa for Starwood and SPG. But now that the programs can all be linked to one another, the added benefits of being members of both programs have increased dramatically.

Members of SPG and Marriott Rewards can now transfer and redeem their points for travel and other exclusive member experiences like access to private concerts, special sports events, and culinary excursions.

For example, Marriott Rewards members can now redeem points for stays in the Maldives, Santorini, and Bora Bora, while SPG members can do the same in Aruba and Kruger National Park in South Africa.

Other perks include access to discounted member rates for hotel stays, although Marriott Rewards Members Rates are only available on Marriott booking channels and SPG Member Rates are only available on SPG booking channels. Booking direct with either Marriott or SPG will also come with free Wi-Fi for members, too.

The complete integration of the loyalty programs is the No. 1 item on Marriott CEO Arne Sorenson’s merger to-do list, and it will be the most carefully scrutinized aspect of the transaction for many months to come.

“The first priority and longest priority is really about the loyalty program,” he told Skift. Of today’s announcement, he said, “I think this is mostly unanticipated. This is a great first step about continuing to evolve that loyalty program into something that is palpably good for every customer, so they understand how worthwhile it is to be a part of the program.”

Sorenson also noted that the three-to-one point exchange was developed so that “the value of the points is the same as they have been in the two systems.”

Travel loyalty program expert, Brian Kelly, of ThePointsGuy.com said, “At one Starpoint for every three Marriott Rewards points, the transfer ratio is beneficial to members of both programs, given that we value Marriott points at 0.7 cents each and Starpoints at 2.5 cents apiece.”

Both programs have traditionally catered to different audiences: SPG has a bigger array of transfer partners and a strong co-branded credit card with American Express, and its loyalty members include a large majority of frequent travelers. Marriott Rewards, by contrast, is a top-ranked loyalty program that makes it easy for members to redeem for free nights. It’s generally more popular with your average leisure travelers, many of whom may not necessarily have elite status.

SPG members have been fairly vocal about voicing their concerns in relation to the merger. Since the deal was first announced, Marriott has gone out of its way to try to allay any concerns the more than 21 million SPG members may have regarding their beloved program. In February, Sorenson went on CNBC to say, “You’ll be OK.”

In recent months, Marriott Rewards, which has 57 million members, has also adopted a few of the features that made SPG so beloved, like more access to one-of-a-kind members-only experiences and concierge services.

Marriott also debuted a massive global ad campaign to promote Marriott Rewards, called “You Are Here,” last week, emphasizing the benefits of being a member.

In April, Starwood also tried to ease SPG members’ minds, telling them that the two programs won’t be merging until 2018. This gives Marriott at least a full year to look at both programs and smooth out any issues related to their full integration.

While it’s too early to tell if SPG or Marriott Rewards members will be pleased with today’s news, another group that may or may not be happy with it consists of the owners of Marriott and Starwood’s hotels. Will they appreciate the fact that they now have an expanded base of loyalty members? Or will the status matching and point transfers and redemptions hurt their bottom lines? We’ll have to wait and see how it plays out.

The Long & Winding Road to the Close

Getting to this point was not at all easy or seamless. This merger was certainly a dramatic one, fraught with a last-minute takeover bid from a mysterious Chinese insurance conglomerate named Anbang. That resulted in a dramatic bidding war, and an even more surprising 11th-hour exit from Anbang Insurance Group. The ensuing battle for Starwood eventually led to Marriott paying about $1 billion more for Starwood than it had first budgeted.

Sorenson told Skift that there was a point in the bidding war where he thought Anbang would prove victorious. “I thought, before Anbang withdrew in late March, there was a meaningful risk, if not a likelihood, in fact, that they were willing to pay more than we were willing to pay and they would end up with the transaction.”

He said that after Anbang initially put in its takeover bid, he and the Marriott team thought very carefully about the deal and what it meant to the company. “We thought, we had put so much work into this, we thought we should put our best offer on the table and hopefully, it’s enough to carry the day. That was by no means certain back in March.”

After both companies’ shareholders agreed to the revised deal in April, it was expected the deal would ultimately close by July. That, too, didn’t turn out as planned, as both Marriott and Starwood had to wait for China’s antitrust regulators to grant their approval, which they ultimately did on Sept. 20.

Sorenson confirmed that the extended antitrust review process in China was “simply the machinery of the Chinese government working.” He added, “We were a little optimistic about how quickly we would get it done, but throughout we had confidence it would get done and it has now finally.”

So, aside from the loyalty programs, what happens now? While it will certainly take months and years for both companies to fully integrate, these will be the key areas of focus for Marriott as it brings Starwood into its fold:

The Executive Reshuffle

As noted before, Marriott expects this deal to generate some $250 million in “synergies” or cost savings, and the bulk of those millions will be saved from executive cuts at the top.

It’s expected that most of Starwood’s top executives will be departing the company either immediately or in the coming months, including current Starwood CEO Thomas B. Mangas.

Marriott will also be inviting some of Starwood’s executives and leaders to the new combined company, including two of Starwood’s board members, Eric Hippeau, partner of Lerer Hippeau Ventures, and Aylwin Lewis, chairman and CEO of Potbelly Corp. They will be joined on Marriott’s Board of Directors by Bruce Duncan, chairman, president, and CEO of First Industrial Realty Trust, increasing the size of its board from 11 to 14.

The departing Starwood executives at the very top may want to send belated thank-you notes to Anbang Insurance Group for its last-minute takeover bid. Thanks to Anbang’s interference, their golden handshakes nearly doubled.

Sorenson said that throughout this merger process, Marriott has been communicating with senior Starwood leadership and he stressed he wanted to “get decisions [about job placements] implemented as quickly as we can so they [Starwood employees] can see the opportunities that are available.”

He added, “We don’t want people to wonder who will fill what job. We want to make those changes quickly. For this deal to be successful, we need it to be for our shareholders, but we don’t do that if it’s not successful for our three principal communities: our associates, our guests, and our owners. We’ve always been associate-focused, and we want them to feel good about the direction this company is going afterward.”

The Culling of Brands

Another aspect of the merger that will be closely watched is the new company’s arsenal of brands — all 30 to be exact. Will Marriott decide to keep all 30? Will it eventually trim the number down to a more manageable portfolio, eliminating any potential duplicates?

We made our educated guesses earlier this week here. It’ll be interesting to see just how accurate our picks are over the next few months and, presumably, years.

However, according to Sorenson, all 30 brands will be staying put.

“We love them all, and we’re going to keep them, and that’s basically the bottom line,” he said. “The strength of the loyalty program isn’t just driven by points but also by the range of choice. Having more brands and hotels and more locations whether they’re resorts, urban, or suburban or 110 countries around the world, lifestyle, luxury, or economy — having those choices drive tremendous strength, so why would we winnow down the brands?”

Sorenson added, “Our contracts [with hotel owners] don’t give us the right to change the names of their hotels. They have deliberately invested in the brand their hotel carries. That too counsels us we should maintain these brands. We want to grow each one of them. We will refine them undoubtedly and evolve brand standards to make them as strong as they can be.”

The Bargaining Power

The power of scale, especially in the hospitality industry, isn’t one to be underestimated. Now that Marriott is the largest hotel company in the world, it’ll have immense bargaining power when it comes to the table to make deals.

This will be especially handy in negotiations with its perennial frenemies, the online travel agencies like Expedia and Booking.com, and when signing contracts with corporate travel managers and meeting planners.

“There’s never been anything like this in the hotel industry ever,” Bjorn Hanson, a professor of hospitality and tourism at New York University’s Tisch Center told Skift. “This is of a scale and importance that’s never been experienced in the industry.”

That scale is also something Sorenson hopes hotel owners, both on the Marriott and Starwood sides, appreciate. “We had our owner advisory councils together in Austin a few weeks ago and they are very supportive of this transaction,” he said. “They understand the strategic significance of this and why it will be and should be good for owners.”

The Merging of Cultures

Another aspect of mergers and acquisitions not often discussed, but as crucial to its success as finding synergies, is the merging of different company cultures. While both Marriott and Starwood have operated for many years as global hotel companies, it’s safe to say they both possess markedly different company cultures.

Marriott is a 90-year-old hotel company with a storied family legacy, based in Bethesda, Md. Starwood, based in Stamford, Conn., is the upstart hotel company first launched by Barry Sternlicht, someone whom Bill Marriott once called “the kid with the backpack.” Since the company’s inception in the 1990s, Starwood has had a knack for being a maverick and an innovator within the hotel industry.

In the midst of the bidding war between Marriott and Anbang, Skift spoke with Ted Teng, president and CEO of Leading Hotels of the World and formerly president of the Asia-Pacific region for Starwood.

Teng said that, having been in the thick of the monumental merger that took place among Sheraton, Westin, and Starwood, he learned this: “Culture will be the most difficult part to execute post-merger. Culture can destroy a lot of value, or it can capture it.”

This concept isn’t lost on Marriott, especially Marriott’s chief human resources officer, David Rodriguez, who will be tasked with bringing together all 500,000 employees — some 300,000 from Marriott and nearly 200,000 from Starwood.

In June, Rodriguez told Skift, “I think when M&A deals fail culturally, it’s because I don’t think companies take the time to listen to both sides and figure out what makes sense. Sometimes it’s not going to be how Marriott does things that’s going to be the best way. It’s going to be something that Starwood is doing.”

He also added, “The other thing I would say is this: Obviously we acquired Starwood, so it’s important that we show respect and acknowledge that they’re a great company that’s done a lot of great things.”

The Technology Involved

While Sorenson believes personnel decisions and the immediacy of the linked rewards programs will be fairly easy to accomplish, he said issues relating to technology will take much longer for the combined company to tackle.

“We have 5,700-plus hotels, with lots of different technology systems that support them,” he said. “How can we quickly integrate them? When? How do we let multiple platforms continue to run? Those issues won’t be resolved until a couple of years out.”

Getting the Word Out

Now that the deal has finally closed, Marriott will also be doing its part to inform consumers that their company has grown dramatically.

On Oct. 14, Marriott will unveil a massive 4,140-square-foot interactive map at New York City’s Rockefeller Plaza, which shows the company’s more then 5,700 hotels. Life-size push pins will also be placed in front of all Marriott and Starwood hotels in New York City.

The event also coincides with a U.S.-based social media sweepstakes through which loyalty members can win one of 30 different travel packages if they share their dream destination with @MarriottRewards or @SPG on Twitter or Instagram, along with the push pin emoji and the hashtags #YouAreHere and #Sweepstakes.

Although it took nearly a year for this acquisition to be completed, the task that lies ahead will be even longer, and Marriott has a lot of work to accomplish.

Photo Credit: Pictured: Le Meridien New Orleans. Marriott's long and winding road to buying Starwood is finally complete. Now, it'll have to figure out how to succeed as the world's largest hotel company. Marriott International