William “Bill” Passo, the founder and CEO of multifamily investment firm Passco Cos., died at age 84.

The company announced that Passo died June 15, and his cause of death was not disclosed. He was still serving as CEO of Orange County, California-based Passco, the company he founded in 1998 that became one of the most active sponsors of Delaware statutory trust offerings, AltsWire reported.

Passo was a pioneer in tenancy-in-common commercial real estate investments, another fractional investment model, and his early work in fractionalized 1031 structures laid the groundwork for the DST market that followed, AltsWire reported.

DSTs allow investors to purchase a fraction of a property offered by a sponsor, satisfying the like-kind requirement of IRS code Section 1031. DSTs are the most common form of securitized 1031 exchanges, a market that surpassed $8B in 2025 for the second time ever.

“Bill was renowned for his innovation … His leadership helped advance the fractionalized 1031 ownership structure and opened new pathways for real estate investors,” Passco said in a statement on LinkedIn. “He was prescient in the truest sense: able to recognize change before it became obvious and adapt with confidence before others understood the moment.”

Real estate finance company Greystone and Passco formed a strategic alliance in 2022 to pursue DST investment opportunities.

Passco’s acquisitions total $8.7B, and the firm manages $4.3B of assets across 17 states. The company is headquartered in Irvine, California, and has a southeast headquarters in Atlanta.

Passco President Larry Sullivan will continue to lead the firm, per AltsWire.

Those who knew Passo will remember his character, the company said in its statement.

“We mourn an extraordinary loss, but we also celebrate an extraordinary life,” the statement said. “Bill leaves behind a legacy in the company he founded, the industry he helped shape, and the countless people whose lives he made better.”