Three executives of New York-based AION Partners have broken off to start their own investment firm focused on acquiring middle-market and workforce multifamily.

Sean Belfi, Craig Boyarsky and Brendan Glavin are behind the private venture, Cold Spring Capital. The three aim to spend $1B to acquire 10,000 apartment units over the next five years through direct acquisitions and joint ventures, they announced in a press release Wednesday.

Belfi, Boyarsky and Glavin all departed AION in December, according to their LinkedIn profiles, and they are no longer on the company's website.

CSC plans to target assets and portfolios with 100 or more units, built since the 1960s, in the Northeast, mid-Atlantic and Midwest. The release says it is prepared to start making deals "immediately.”

“We are ready to hit the ground running in 2026 to source deals and scale operations in what we view as a favorable market environment for conventional, market-rate workforce housing,” Belfi said.

The equity for Cold Spring Capital's initial acquisitions is poised to come from New York-based Twin Spruce Capital, a close syndicate of high net worth and ultra-high net worth investors. Twin Spruce has historically taken preferred equity positions in multifamily deals, and its partnership with CSC marks its entry into traditional multifamily equity investments.

In the release, Belfi pointed to four tailwinds he said are backing the locations and types of assets the firm is targeting: market stabilization, occupancy and rent growth resilience, the strategic dislocation of assets in operational or capital distress, and wider cap rates for pre-2000 assets.

“We believe that there will always be a continued drip of private owners that look to sell for non-market reasons, like estate-planning or disposition of non-core assets,” he said.

“These types of owners are often motivated by different investment goals and typically operate their assets in ways that are not considered industry-standard, which results in an operational arbitrage opportunity,” he added. “Based on national ownership figures, there are more of these types of private owners in our geographic markets than elsewhere in the country.”

Belfi, who was at AION for 11 years, was most recently a principal. Boyarsky and Glavin were most recently vice presidents. They were with the firm for eight and 10 years, respectively. The release says they were all “active in acquisitions, asset management, and investor relations across both single-asset ventures and multiple discretionary fund vehicles.”

AION has a 20,000-unit portfolio across 62 communities, largely located in the mid-Atlantic and Midwest.