Daughter of prominent Philadelphia family sues billionaire ex-boyfriend for $400 million

Some romantic rendezvous end in heartbreak, others in a $400 million lawsuit.

But that’s the fall out from the breakup between Oona Sperr, the daughter of the Please Touch Museum founder and a prominent Philadelphia architect, and an oil-tycoon from Texas.

In a tell-all lawsuit, Sperr, 64, accused billionaire Sid Bass of breaking financial promises he made to her throughout their relationship.

The New York City-based interior designer and Bass “lived together in a loving, committed relationship” since 2014 and “were very happy as a couple,” the suit says. The oil scion, has a net worth of $4.4 billion, promised Sperr that she would always be cared for financially and would receive ownership interest in his properties, according to the complaint.

The 84-year-old began declining physically and cognitively in 2023, the suit says. He previously suffered three mini-strokes, signs of Parkinson’s disease appeared in a brain scan, and his excessive drinking worsened his tremors, the complaint says.

Around that time, Althea Viafora Kress entered the picture.

Viafora Kress pursued Bass since late 2022 under the pretext that she needed advice on how to invest money she inherited, the suit says.

“Unbeknownst to Oona, Viafora Kress began grooming Sid and, at some point, achieved her goal of a coercive relationship with him, with devastating consequences for Oona and Sid’s partnership,” the complaint says.

After breakfast in September 2024, the suit says, Bass broke up with Sperr with two sentences: “I want a separation. You are to pack and leave.”

Sperr suspected that there was another woman, and in the following weeks she came to learn about Bass’ relationship with Viafora Kress.

Immediately after the breakup, the suit says, Bass promised his former paramour a lump-sum payment of $50 million, the smallest of their New York homes, another property of her choosing, continued staff support, and care for her mother, the 96-year-old founder of the Please Touch Museum, Portia Sperr.

These terms were less than Bass originally promised her, the complaint says. But in the following months, the commitment narrowed further.

Sperr received a “maintenance agreement” via email from Bass’ lawyer in January 2025 that included a commitment for annual payments of $5 million for 10 years, denied her ownership of any home, and declined to pay for her mother’s care, among other things, the suit says. The agreement was also accompanied with a nondisclosure agreement.

“In other words, what Sid was now proposing was that Oona … should be forced to depend entirely on Sid’s increasingly unpredictable whims, or, even more troubling, on the preferences of Viafora Kress,” the lawsuit says.

The Inquirer was unable to reach Bass and Viafora Kress, who are both named defendants in the lawsuit, which was filed in the Southern District of New York.

While a $400 million breakup is more than most could wrap their head around, it’s par for the course for Bass, the suit says.

The billionaire previously had two extremely expensive divorces.

Bass divorced his first wife, Anne Hendricks Bass, in 1988, leading to settlement that cost him $200 million to $500 million, the suit says. And in 2011 he divorced Mercedes Bass in an agreement that would allow her to sustain an “ultraluxury lifestyle,” according to the complaint.

“This is a case about broken promises,” Roberta Kaplan, Sperr’s attorney, said in a statement. “Oona is the woman who spent a decade making Sid’s life convenient — abandoning her career, managing their shared homes and affairs, caring for him through his serious illnesses — all because Sid agreed that he would take care of her and her 96-year-old mother no matter what.”

While Sperr comes from a more modest upbringing relative to the son of an oil dynasty, her family has a legacy of its own in Philadelphia.

Her father, Otto Sperr, was a prominent Rittenhouse Square architect. He died in 1998.

Portia Sperr was a Montessori educator who still lives in Philadelphia, the suit says.

Oona Sperr moved to Philadelphia when she was 2, and went on to graduate from the Baldwin School in Bryn Mawr. She then moved to New York to study architecture and embarked on a career as an interior designer.

But she abandoned that career after meeting Bass, opting to take care of him, their homes, and daily obligations because of a promise that she would never need to support herself or her mother independently.

“Sid has breached his promises by refusing to provide Oona with the property interests and financial support he agreed she would receive,” the suit says, “in exchange for her years of devotion to their partnership and her enormous contributions to the life they built together.”