A New York interior designer who spent a decade as the companion of Texas oil billionaire Sid Bass is suing him for $400 million, claiming he verbally promised her a $50 million lump sum, a home of her choosing, and lifetime care for her mother before abruptly cutting her off in September 2024. Oona O. Sperr's federal lawsuit also names Bass's new wife, art advisor Althea Viafora Kress, accusing her of manipulating the 84-year-old and taking advantage of his cognitive decline to steer him away from his earlier commitments.
According to The New York Times, Sperr and Bass were never formally married but were introduced as partners at society parties from 2014 to 2024. The two agreed to build their lives together after Bass invited her to lunch at his townhouse on East 94th Street in January 2014, and Sperr says she gave up her own career and went on to manage multiple Upper East Side townhouses that Bass owned. The complaint puts Bass's net worth at no less than $4.4 billion.
Sperr's attorney, prominent litigator Roberta Kaplan, framed the case in stark terms, saying that for a decade Sperr “made Bass's life convenient” and that the lawsuit is ultimately about broken promises. Bass allegedly told Sperr to move out in September 2024, saying he wanted a separation — a request the complaint links to his diagnosis with Parkinson's disease.
A Verbal Offer, Then a Very Different Contract
Just weeks after telling Sperr he wanted to separate, Bass verbally offered her a $50 million lump-sum payment, according to the suit. Less than a month later, his lawyers sent Sperr a letter titled “maintenance agreement” that told a different story: instead of the promised lump sum, it offered $5 million in annual payments spread over 10 years, required Sperr to sign a nondisclosure agreement, abandoned his earlier commitment to pay for her mother's care, and conditioned her housing on tenancy rather than ownership — explicitly denying her title to any home.
Bass had also given Sperr a 25-carat diamond during their relationship, the complaint states, and had promised to give her a home in New York outright as part of the arrangement she says he later reneged on. Sperr says she learned of Bass's marriage to Kress not from him directly but through a six-sentence email with the subject line “news.”
Kress Accused of Directing the Financial Break
The lawsuit accuses Kress, whom Bass married in August 2025, of directing Bass to cut Sperr off financially and of manipulating him during a period of cognitive decline. According to background compiled by Clocktower.org, Kress is a longtime New York art advisor and former gallery owner who ran the Althea Viafora Gallery and previously worked with the international gallery Hauser & Wirth. Neither Bass nor Kress responded to requests for comment on the lawsuit, the Times reports.
Because New York does not recognize common-law marriage or implied cohabitation contracts, Sperr's legal team faces a steep burden: under the state's 1980 Court of Appeals precedent in Morone v. Morone, courts will enforce express oral or written financial promises between unmarried partners but will not infer obligations from years of domestic partnership alone, according to a case analysis published by Studicata. That legal standard means Sperr must prove Bass made clear, explicit promises rather than relying on the years she spent managing his homes and household.
A Pattern of High-Stakes Marriages and Settlements
This is not Bass's first marriage to end amid eye-popping financial stakes. His first marriage, to Anne Hendricks Bass, ended in 1988 after he left her for Iranian-born socialite Mercedes Kellogg; the two were reportedly discovered together at the Hôtel Plaza Athénée in Paris. Anne Hendricks Bass received at least $200 million in cash along with more than one million Disney shares, artwork, and real estate — a settlement reportedly cited as the largest in Texas history at the time, per background compiled by Old Money Luxury.
Bass married Kellogg at the Plaza Hotel in New York in 1988 — the same year his brother Robert Bass sold that hotel to Donald Trump for $390 million. Mercedes Bass went on to serve as the Metropolitan Opera's longtime managing director; she and Bass split in 2011 after 23 years of marriage, according to reporting from Gramilano.
The Scale of Bass's Fortune
Bass's liquid wealth stems in large part from a January 2017 deal in which he personally negotiated the sale of the Bass family's 275,000 acres of Permian Basin oilfields to ExxonMobil for $6.6 billion in stock and contingent payments — a transaction that doubled ExxonMobil's Permian Basin holdings, according to KERA News. He was also once the largest individual shareholder in The Walt Disney Company after building a major stake in 1984, though he was forced to liquidate 135 million shares for roughly $2 billion in September 2001 amid a market downturn, representing about 6.4 percent of Disney's outstanding shares at the time, the Los Angeles Times reported.
Locally, Bass has been in the news before: Hoodline previously reported on his $125 million emergency financing facility that rescued Blue Bell Creameries after its deadly 2015 listeria outbreak, a deal that secured him a one-third ownership stake in the century-old Texas creamery. That case, too, is now working its way back through Delaware court.
Sperr's suit, filed in New York federal court, seeks $400 million — a figure that dwarfs even the historic settlement Bass's first wife received nearly four decades ago. Whether Sperr can meet New York's demanding legal standard for proving explicit promises, rather than an implied arrangement built over a decade of shared life, will likely determine the outcome of a case that has already drawn attention for its collision of old money, new marriage, and a fortune built on Texas oil.
