Mainstay Raises $18M and Acquires Truelist

Mainstay, a system of record for residential real estate, announced that it raised $18 million and acquired Truelist, an artificial intelligence-powered listing platform for brokers and agents.

Carved out of Opendoor as an independent company in August 2024, San Francisco-based Mainstay combines proprietary data, pricing intelligence, and agentic automation to replace fragmented systems and manual workflows across buying, owning and selling homes. Its founding team spent more than a decade building and operating residential real estate technology and infrastructure at scale.

The financing includes new investors Parker89, Stackpoint, Alpaca VC, and FJ Labs, alongside existing investors Khosla Ventures, Era Ventures and Clocktower Technology Ventures. Mainstay will use the capital to accelerate its expansion into brokerage and working with smaller investors, the company announced in a statement.

“Residential real estate pricing has historically been far more opaque than it should be because the underlying data is fragmented and often inaccurate,” Mainstay CEO and co-founder Dod Fraser said in an email. “By bringing together property data, market data and real-world outcomes into a continuously updated property record, we can give owners, brokers and agents much more transparent and accurate visibility into what a home is worth and why. This transparency and accuracy allows all participants to work with the same information, improving everyone’s ability to make better decisions.”

Seattle-based Truelist founder and CEO Carey Armstrong is joining Mainstay as chief strategy officer. Armstrong previously served as vice president of Zillow’s Premier Agent business, and co-founded and served as chief operating officer of life-coaching AI firm Tomo.

Founded in 2024, Truelist built an AI-powered listing platform to help real estate brokers and agents manage, create and distribute property listings across Multiple Listing Service systems.

“Mainstay and Truelist have been attacking the same broken system from different angles — Mainstay on behalf of investors, Truelist on behalf of brokers and agents,” Armstrong said in a statement. “Joining forces means we stop duplicating effort and start compounding it. I have enormous respect for what Dod and the team have built, and I’m excited about what we can do together.”

Mainstay said it has facilitated more than $12 billion in residential real estate transactions and executed more than 2 million agentic workflows.

“Mainstay and Truelist are both unusual in that their teams have actually built and operated these systems at scale inside the industry’s largest and most innovative residential platforms,” Clelia Peters, managing partner of Era Ventures and a Mainstay board member, said at the time of the acquisition. “The combination of deep residential real estate experience, a well of proprietary data, and an innovation and AI-first approach is unique in the industry, and creates an opportunity to build something foundational.”

Philip Russo can be reached at prusso@commercialobserver.com.