A billionaire oil heir brutally ditched his long-term girlfriend at their expansive Colorado ranch before quickly marrying his socialite mistress, a lawsuit has claimed.
Sid Bass, 84, abruptly cut ties with his partner of ten years Oona Sperr, 64, in September of 2024, a lawsuit filed in federal court this week by Sperr and seen by the Daily Mail claimed.
A blindsided Sperr claimed in her suit that their relationship crumbled after Bass, worth at least $4.4 billion, was ‘groomed’ for two years by socialite Althea Irene Viafora Kress, 68, who Bass has since married.
Things came to a head in 2024 inside the couples Pagosa Springs, Colorado, ranch over their typical breakfast of dairy free yogurt and berries when Bass told her: ‘I want a separation. You are to pack and leave,’ according to Sperr’s lawsuit.
Sperr, who is suing Bass for $400 million, said that she asked her then boyfriend if there was someone else due to what she described as his ‘well-known history of cheating on his previous wives,’ her lawsuit alleges.
Sid Bass and his ex-girlfriend Oona Sperr seen in Venice in 2015. Bass, an oil billionaire, dated Sperr for 10 years. She is now suing claiming she was brutally dumped for another woman and that financial promises Bass allegedly made were not kept
Bass is pictured with wife Althea Irene Viafora Kress at a MoMA event in New York in June 2026. Sperr has accused Kress in a civil complaint of maneuvering her way into Bass’s affections, with the couple marrying in August 2025
Bass denied cheating before allegedly offering her a lump sum of $50 million, a home in New York City and another address of her choosing to leave quietly, the suit added.
In the days after, while clearing her belongings from the Colorado estate, she heard him talking on the phone to Kress and referring to her as ‘sweetheart’ – the term of endearment he had previously reserved only for Sperr, her suit claimed.
Kress allegedly ordered Bass never speak to Sperr again, ordered him to gut their many homes of her possessions – and even warned him not to drive her to the airport to say their final goodbye, Sperr’s lawsuit claims.
Bass was a heavy drinker who had suffered three mini-strokes and who had been diagnosed with Parkinson’s disease by the time he dumped Sperr, she alleged in her legal filing.
She further accused Kress of manipulating Bass and taking advantage of his alleged cognitive decline to begin a relationship with him and shove Sperr out, the filing claims.
Bass and Kress’s relationship blossomed and they wed on Bass’s private Texas island in August 2025. The couple were later photographed smiling at a MoMA event in New York in June.
Sperr said Bass sent her this email announcing his wedding to Kress, although she speculated in her lawsuit whether it had actually been written by Kress herself
Sperr shared a photo of Bass’s private jet in one of his family’s hangars in her legal filing
The ceremony took place on the sandy enclave where Sperr and Bass had once enjoyed long walks collecting rare sea shells, according to her lawsuit.
Sperr said she was only informed of the nuptials via a six line email from Bass two weeks later, which she claims to have reproduced in full in her lawsuit.
It said: ‘Althea and I were married on Saturday, August 9th at San Jose Island. Hyatt, Samantha and grandsons, plus Lee and Ramon attended.
‘Althea’s seven closest friends attended’, the email continued before blurring out three people named as Bass’s best men and ended: ‘Althea will change her name to Viafora-Bass.’
According to Sperr, the email was not composed or sent by her ex-partner but Kress who has ‘taken over Sid’s life, including his electronic communications’, her suit said.
The email was the final nail in the coffin of what Sperr described in her suit as being a ‘loving’ and ‘committed’ decade-long relationship.
Sperr described in her suit how they first met in the summer of 1995 in Rome while Bass was married to his second wife, socialite Mercedes Tavacoli Kellogg Bass.
She said that despite just meeting ‘their conversation quickly took on an unexpected ease and familiarity,’ the suit said.
Sperr also shared a photo of an enormous diamond ring she says Bass gave her in front of a Vincent Van Gogh painting that sits in their bedroom
Bass and his first wife Anne Bass in 1986. She is mother to the couple’s two eldest children, with the marriage ending in a $200 million to $500 million divorce after Bass was caught cheating, the suit said
Bass and his second wife Mercedes. The couple’s affair was the biggest high society scandal of the 1980s and triggered a monster divorce payout, the suit said
It added: ‘That early moment of connection in Italy would grow into a loving partnership that would come to define the next decade of their lives.’
Bass and Mercedes divorced in 2011 with Mercedes being handed an undisclosed lump sum as well as annual allowances, a Texas estate and an apartment on Manhattan’s Fifth Avenue, the suit said.
Sperr’s suit detailed how Bass was infamously caught cheating on first wife Anne Hendricks Bass with Mercedes in Paris in 1988, with the ensuing divorce one of the high society scandals of that decade.
Anne, the mother to two of his children, was given between $200 million and $500 million in the wake of the split, Sperr said in her suit – equivalent to up to $1.4 billion in 2026.
After what Sperr described as a ‘chance encounter’ with Bass following his divorce from Mercedes, the two started dating.
Bass confided in her that he wished to put the high-society lifestyle behind him to become a humble painter, her lawsuit added.
Sperr included multiple photos of Bass’s artwork in her filings, including a bizarre high concept ‘self-portrait’ that features an outline of Bass behind a stop symbol, above the words ‘Jesus Saves.’
She described how he spoke of his ‘unhappiness during his marriage to Mercedes’ and what the suit described as ‘relentless social obligations that she had imposed on him.’
Bass and second wife Mercedes in 2007. Oona Sperr claims in her lawsuit that Bass grew tired of Mercedes’s high-society socializing
In the ensuing years, Sperr described her life as living in ‘Bass Land,’ flying on a $55 million Gulfstream jet owned by Bass and living in luxury homes in Colorado, Texas and Manhattan which they decked out in original work by Van Gogh, Monet, Matisse, Picasso, Rothko and Warhol, the suit said.
Sperr shared a photo of herself with what she called the couple’s Van Gogh in her lawsuit.
The two mainly resided inside a $26 million double-fronted townhouse in the Upper East Side of Manhattan, according to the suit.
A multi-million dollar house just for guests was bought nearby, with Sperr keeping herself busy maintaining her husband’s property empire and managing his many staff, according to her lawsuit.
Bass’s Pagosa Springs estate in Colorado – where he dumped Sperr – stretched to seven properties spread out across a ridgeline with a 7,000 acre ranch, the suit said.
There was also a huge loft in Fort Worth, Texas, comprised of three units combined.
When not living in one of their many mansions, Bass and Sperr would use the private jet to travel to Santa Fe and Paris, according to Sperr’s suit.
She conceded it was a rapid change in circumstances from her previous life living in a New York City apartment, but Sperr insists she was only attracted to Bass because of his personality.
Sperr and Bass pictured together in London in June 2023. Her lawsuit accused the oil heir of having health issues including a drinking problem
Bass and Sperr seen in Nebraska in 2017. Sperr’s lawsuit said that Bass loved painting and that the couple would walk the sands of the Bass’s private island to look for rare sea shells
‘This was the world Oona (Sperr) agreed to manage, maintain, and make into a home as Sid’s partner,’ the suit said.
It added: ‘Almost immediately, Oona found herself responsible for designing and monitoring the progress of renovations, long-term planning, and supervising staff, including housekeepers, landscapers, and security personnel.
‘Oona’s responsibilities extended beyond managing the couple’s homes. Consistent with Sid’s expressed desire for a quieter life after Anne and Mercedes, Oona worked alongside him to create the more private and serene environment he wanted’, the suit continued.
It added: ‘The trappings of “Bass Land” were never what really mattered to her. Throughout her life, Oona had been around plenty of high-society individuals.
‘But that is not what attracted Oona to Sid. Oona loved him for his gentler, artistic side – the part of him that had always wanted to be, and is, an impressive painter.’
She said this new life was also not without its problems, describing in the suit how the pair had also been frequently ‘stalked and harassed’ by a former lover of Bass.
The suit identified the woman as Patricia Zohn Pfeiffer, who Sperr said Bass later revealed he had an affair with while married to Mercedes, according to the legal filing.
For those closest to the couple ‘there was no question in anyone’s mind that Oona was Sid’s partner for life,’ the suit added.
She described how he made ‘tangible gestures’ to demonstrate his ‘deep and lasting commitment to Oona’ which included a 25.6 carat diamond ring worth $2.1 million, the suit said.
On top of the diamond, an image of which Sperr shared in the suit, he also gave her a 20-carat emerald worth $1 million, the suit said.
Besides material goods, the suit said that Sperr was appointed power of attorney over his affairs and his health care proxy.
The suit continued: ‘Oona expected to spend the rest of her life with Sid, devoted to his health and happiness.
Bass is seen in 2017. He has yet to respond to his ex-girlfriend’s legal filing
‘Their relationship unfolded in an atmosphere of mutual trust and affection, grounded in the shared understanding that their life together would continue until one of them died.
‘Sid repeatedly affirmed that promise to Oona, assuring her that she was provided for and that his specific commitments to her would be honored.’
It is also claimed that despite saying he would give her $50 million and two homes, his lawyers instead sent Sperr an agreement for her to sign in which she was to be given $5 million annually for ten years.
She also said in the suit that he attempted to silence her by forcing non-disclosure agreements about their relationship on her.
Sperr is now seeking the sum due to having ‘relied on Sid’s promises to her detriment and suffered an unconscionable injury.’
The suit also frequently mentions Kress as having intentionally interfered in their relationship and caused the alleged damages
Roberta Kaplan, an attorney for Sperr, shared with the Daily Mail what is reflected in the complaint, saying: ‘This is a case about broken promises. Sid Bass is a billionaire at least four times over.
‘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.
‘After accepting all the benefits, Sid abruptly ejected Oona, breaking his promises to her.
‘Because Sid has failed to keep his word, Oona, now 64 years old, had no choice but to bring this case.’
The Daily Mail approached Bass and Kress for comment. They have yet to file a response to the suit, court records show.
