Oil billionaire Sid Bass offered his former girlfriend $50 million and round-the-clock security for her elderly mother if she agreed to leave his life permanently, according to court filings.
Bass, 84, is seeking to sever ties with Oona Sperr, 64, after ending their relationship over breakfast at his Colorado ranch in September 2024, the filings say.
Bass, whose fortune is estimated at no less than $4.4 billion, and his third wife, Althea Irene Viafora Kress, 68, have both been sued by Sperr.
Sperr claims Bass should provide the financial benefits she would have received as a wife had they divorced. She is seeking $400 million. Bass denies her allegations and the claims brought against him.
The latest court filing, obtained by Our News Outlet, details what Bass allegedly offered Sperr at the start of settlement discussions.
Under the proposal, Bass would have paid Sperr $5 million annually for 10 years after their breakup, according to the document.
The offer also included covering costs associated with the care and support of Sperr’s mother, Portia. Sperr ultimately rejected it, the filing says.
The document states: ‘[Portia] will be provided with security services (door access, alarms, monitoring and a 24/7 staffed security post) for the remainder of her life.’
Bass made the proposal on the condition that Sperr sign a non-disclosure agreement, according to the filing.
She declined. The former couple are now engaged in settlement negotiations, although the possible terms remain confidential.
Sperr and Bass pictured together in London in June 2023. The oil billionaire dated Sperr for 10 years. She is now suing, claiming he abruptly left her for another woman and failed to honor financial promises he allegedly made
Bass is pictured with his 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; the pair married in August 2025
Kress was also named as a defendant in Sperr’s lawsuit.
Last month, Kress responded to the complaint in a filing that could serve as a pointed reminder to Sperr that she ultimately won Bass’s affections.
Kress asked to be identified by her married name, Althea Bass, in future court documents.
She also requested that all claims against her be dismissed, although Judge Ronnie Abrams has not yet heard her arguments.
In a joint letter filed with Sperr’s attorneys, Bass’s representatives said he disputed her ‘characterization’ of their earlier settlement discussions.
They argued that the case should be dismissed because of alleged ‘fatal deficiencies’ and described it as ‘frivolous.’
‘Plaintiff falsely attacks Mr. and Mrs. Bass’s good character, misrepresents Mr. Bass’s health, omits Mrs. Bass’s decades of independent accomplishments, ignore Defendants’ forty-year friendship, and her claims fail as a matter of law’, they claimed.
In her lawsuit, Sperr said she confronted Bass about suspected infidelity during their conversation that morning in 2024.
She said her concerns were based on Bass’s ‘well-known history of cheating on his previous wives.’ Bass was married to Anne Hendricks from 1965 to 1988 and Mercedes Kellogg from 1988 to 2011.
Sperr said Bass denied being unfaithful. She later claimed she overheard him speaking by phone with Kress and addressing her as ‘sweetheart.’
According to Sperr’s complaint, Kress told Bass never to speak with her again, instructed him to remove her belongings from their numerous homes and warned him not to drive her to the airport for a final farewell.
Sperr also alleged that Bass was a heavy drinker, had suffered three mini-strokes and had been diagnosed with Parkinson’s disease by the time he ended their relationship.
Bass is seen in 2017. He is currently involved in settlement discussions with his former girlfriend after she sued him
Bass and Sperr are seen in Nebraska in 2017 in a photograph filed with her lawsuit. Sperr said Bass denied cheating, but claimed she later heard him call Kress ‘sweetheart’ during a phone conversation
Sperr further accused Kress of manipulating Bass and exploiting an alleged decline in his cognitive abilities to begin a relationship with him and push her aside, according to the complaint.
Court papers filed late last month referred to that alleged decline. Sperr’s attorneys claimed Bass was experiencing strokes, neurological problems and memory loss.
Bass and Kress’s relationship developed, and they married on his private Texas island in August 2025. The couple were later photographed smiling at a MoMA event in New York in June 2026.
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Sperr said she learned of the wedding through a six-line email from Bass sent two weeks afterward. She reproduced what she said was the full message in her lawsuit.
It read: ‘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 three names, identified as Bass’s best men, were obscured. It ended: ‘Althea will change her name to Viafora-Bass.’
Sperr alleged that Kress, rather than Bass, had written and sent the message, claiming Kress had ‘taken over Sid’s life, including his electronic communications.’
Sperr said Bass sent this email announcing his wedding to Kress, while questioning in her lawsuit whether Kress had actually written it
Sperr included a photograph of Bass’s private jet inside one of his family’s hangars in her court filing
Sperr described the email as the final blow to what she characterized in her lawsuit as a loving, committed relationship that had lasted a decade.
She said they first met in Rome during the summer of 1995, while Bass was still married to his second wife, socialite Mercedes Tavacoli Kellogg Bass.
Bass and Mercedes divorced in 2011. She received an undisclosed lump sum, annual allowances, a Texas estate and an apartment on Manhattan’s Fifth Avenue, according to Sperr’s lawsuit.
The complaint also described how Bass was allegedly caught cheating on his first wife, Anne Hendricks Bass, with Mercedes in Paris in 1986. Their subsequent divorce became one of the decade’s major high-society scandals, Sperr claimed.
Anne, the mother of two of Bass’s children, received between $200 million and $500 million after the split, according to Sperr’s lawsuit. That figure would be worth as much as $1.4 billion in 2026.
After what Sperr called a ‘chance encounter’ with Bass following his divorce from Mercedes, the pair began dating.
Sperr said she subsequently lived in what she called ‘Bass Land,’ traveling aboard his $55 million Gulfstream jet and residing in luxury properties in Colorado, Texas and Manhattan. The homes were furnished with original works by Van Gogh, Monet, Matisse, Picasso, Rothko and Warhol, the lawsuit states.
She included a photograph of herself with what she identified as the couple’s Van Gogh in the complaint.
The couple primarily lived in a $26 million, double-fronted townhouse on Manhattan’s Upper East Side, according to the lawsuit.
Bass and Sperr are pictured together in Venice in 2015
Sperr also submitted a photograph of a large diamond ring she said Bass gave her, shown in front of a Vincent Van Gogh painting displayed in their bedroom
Bass and his second wife, Mercedes, in 2007. Sperr alleges in her lawsuit that Bass eventually tired of Mercedes’s high-society social schedule
A nearby multi-million-dollar property was purchased exclusively for guests. Sperr said she spent her time managing Bass’s staff and helping maintain his extensive property portfolio.
Bass’s Pagosa Springs estate in Colorado, where he ended the relationship, encompassed seven properties spread along a ridgeline and included a 7,000-acre ranch, according to the complaint.
The couple also had a large loft in Fort Worth, Texas, made up of three combined units.
When they were not staying at one of their many residences, Bass and Sperr traveled by private jet to destinations including Santa Fe and Paris, the lawsuit says.
Sperr acknowledged that the lifestyle represented a dramatic shift from her earlier years in a New York City apartment. However, she maintained that she was drawn to Bass for his personality rather than his wealth.
She said Bass made ‘tangible gestures’ reflecting his ‘deep and lasting commitment to Oona,’ including giving her a 25.6-carat diamond ring valued at $2.1 million, according to the lawsuit.
He also gave her a 20-carat emerald worth $1 million, the complaint says. Sperr included an image of the diamond in her filing.
Beyond the jewelry and other gifts, Sperr said Bass appointed her his power of attorney and health care proxy.
She is now seeking damages, saying she ‘relied on Sid’s promises to her detriment and suffered an unconscionable injury.’
The lawsuit repeatedly accuses Kress of deliberately interfering with Bass and Sperr’s relationship and causing the financial harm Sperr claims to have suffered.
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