In the fast-moving world of real estate technology, change often arrives not with a dramatic hammer blow but with a quiet, strategic handshake between companies that see the same problem from different angles. That is exactly what happened when Seattle-based real estate tech startup Truelist was acquired by San Francisco-based Mainstay, a deal announced alongside an $18 million growth funding round meant to push AI-powered tools deeper into the residential property market. For those who have been watching the space, the acquisition feels less like an ending and more like a turning point—two teams with complementary strengths deciding that together they can move faster than they ever could apart. The transaction also signals something larger: the real estate industry, long seen as slow-moving and relationship-driven, is finally becoming a true technology sector, where data, automation, and artificial intelligence are not optional extras but essential infrastructure. With Mainstay aiming to expand beyond its institutional roots and Truelist bringing its broker-friendly listing platform into the fold, the deal has the potential to reshape how property listings are created, distributed, and managed across the country. It is, in many ways, a story about recognizing inefficiency and having the courage to do something about it.
Truelist itself was born from a painfully familiar frustration: the fragmented, outdated, and often maddening world of Multiple Listing Services, or MLS systems. For real estate brokers and agents, these systems are supposed to make life easier by providing a centralized database of properties for sale. In reality, they are a patchwork of regional platforms, each with its own rules, formats, quirks, and inefficiencies. Getting a listing live across all the relevant channels can require hours of tedious data entry, formatting adjustments, and manual updates. Truelist wanted to change that. Founded in 2024, the startup built an AI-powered listing platform designed specifically to help brokers and agents manage, create, and distribute property listings across these fragmented systems with far less friction. Instead of treating each MLS as a separate hurdle, Truelist treated them as part of one interconnected network, using artificial intelligence to streamline the process from start to finish. The result was a tool that saved real estate professionals time, reduced errors, and made it easier to get properties in front of potential buyers. It was the kind of behind-the-scenes innovation that doesn’t always make headlines, but it makes an enormous difference to the people who actually do the daily work of buying and selling homes.
The woman behind Truelist, Carey Armstrong, is no stranger to the challenges and opportunities of real estate technology. Her career reads like a tour through some of the most important moments in the industry’s digital transformation. She spent seven years as vice president of Premier Agent at Zillow, the giant online marketplace that changed how people shop for homes. In 2020, she co-founded Tomo, a real estate fintech startup that aimed to make the homebuying process smoother and more transparent. Tomo was founded alongside Greg Schwartz, another former Zillow leader, and it quickly attracted serious attention, raising a $40 million seed round backed by a who’s who of real estate tech luminaries, including former Trulia CEO Pete Flint and former Zillow chief executive Spencer Rascoff. Armstrong served as Tomo’s chief operating officer, learning the operational side of building a company from the ground up. After that experience, she launched Truelist in 2024, bringing all of that accumulated knowledge to bear on the MLS problem. Her journey reflects a particular kind of persistence—someone willing to take on hard problems, learn from each attempt, and keep building. In her own words, she expressed gratitude to everyone who supported Truelist along the way, and especially to the team who put so much talent, care, and hard work into building the platform. “If you don’t know Mainstay yet,” she wrote on LinkedIn, “don’t worry, you will soon.”
For those who do not yet know Mainstay, here is the background. The company was carved out of Opendoor, the real estate marketplace known for its iBuying model, as an independent startup in August 2024. It was led by Dod Fraser, formerly president of Opendoor, along with fellow Opendoor veterans J.D. Rasmussen and Michael Dulfer. Mainstay operates what it calls an “intelligent system of record” for residential real estate—a way of automating data and transactions across the entire lifecycle of a property, from acquisition to disposition. Its primary clients have been large institutional investors, the kind of players who own and manage thousands of homes and need sophisticated technology to keep track of everything. The results so far have been impressive: Mainstay says it has facilitated more than $12 billion in real estate transactions and serves 95% of the 60 largest residential real estate investors in the country. That is a remarkable achievement for a company that only became independent in 2024. It means Mainstay already sits at the center of the institutional side of the market, handling enormous volumes of data and helping some of the biggest names in the industry operate more efficiently. But the company knew that the institutional segment, while lucrative, is only one slice of the residential real estate pie. To truly build the intelligent system it envisions, Mainstay needed to reach down into the broader market of individual agents, small brokerages, and smaller property owners—and that is exactly where Truelist came in.
This acquisition is not just about adding a tool to a product lineup; it is about expanding the entire vision of what real estate technology can be. For Mainstay, the deal provides a ready-made bridge into the world of brokerages and agents, who have historically been underserved by institutional-grade technology. Many of these professionals operate as independent contractors or within small teams, and they simply don’t have the resources to build custom solutions for the MLS chaos they deal with every day. Truelist gives them a powerful, AI-driven platform that handles the heavy lifting of listing management, allowing them to spend more time with clients and less time wrestling with data entry. For Truelist, joining Mainstay means access to far greater resources, data, and reach, allowing its platform to scale in ways that would have been difficult, if not impossible, as a standalone startup. Armstrong framed the union beautifully, saying, “Joining forces means we stop duplicating effort and start compounding it.” It’s a phrase that captures the central logic of the deal: two companies, each with its own strengths, choosing to combine rather than compete. Armstrong will take on the role of chief strategy officer at Mainstay, a position that reflects not only her experience but also the strategic importance of the Truelist platform to Mainstay’s future. It also ensures that the knowledge and relationships she has built over her career will remain part of the expanded company’s DNA.
Looking ahead, the implications of this deal extend far beyond the two companies themselves. The $18 million funding round that accompanied the acquisition included backing from a range of notable investors, such as Khosla Ventures, Era Ventures, Parker89, Stackpoint, Alpaca VC, and FJ Labs. That roster of backers signals confidence not just in Mainstay and Truelist, but in the broader thesis that artificial intelligence will fundamentally reshape residential real estate. For years, the industry has been criticized for lagging behind other sectors in adopting technology. Paperwork, manual processes, and fragmented systems have long been the norm. But the wave of innovation that brought us online listings, digital mortgages, and iBuying is now turning its attention to the underlying plumbing of the industry—the data standards, the transaction workflows, and the listing distribution systems that make everything else possible. Mainstay’s goal is to become the connective tissue, the system of record that everyone from the largest institutional investor to the independent agent can rely on. With Truelist in the fold, that goal becomes much more attainable. The acquisition also speaks to the power of human relationships in an increasingly digital world. Armstrong and Fraser both come from the same tight-knit Seattle and Silicon Valley real estate tech circles, and this deal is as much about trust and respect as it is about strategic alignment. Armstrong’s gratitude toward her team and her excitement about the future came through clearly in her public comments, and Fraser’s willingness to bring her into the leadership team shows a leader who values talent and culture as much as technology. In a world where acquisitions often lead to awkward integrations and clashing cultures, this one appears to be different—a partnership forged from shared experience and a common mission. The real test, of course, will be in the execution. Merging platforms, teams, and product roadmaps is never easy. But if the early signs are any indication, the combination of Truelist’s listing intelligence and Mainstay’s transactional backbone could create something genuinely new: a seamless, intelligent layer over the entire residential real estate market. That would be good news for agents, good news for investors, and above all, good news for the millions of people who simply want to buy and sell homes without the unnecessary headache. The deal is a reminder that even the most entrenched industries can be transformed, one thoughtful acquisition at a time.
