A version of this article first appeared in CNBC’s Inside Wealth newsletter with Robert Frank, a weekly guide to the high-net-worth investor and consumer. Sign up to receive future editions, straight to your inbox.

Super PACs supporting Andrew Cuomo and opposing Zohran Mamdani in the New York City mayoral race have raised over $40 million, with millions coming from prominent billionaires and family dynasties, according to election filings.

New York billionaires Bill Ackman, Ronald Lauder, William Lauder, Barry Diller and Dan Loeb have all made large donations to a special committee called Fix the City that supports independent candidate Andrew Cuomo, according to election filings. Other non-New Yorkers giving to the group include casino mogul Steve Wynn and Alice Walton, the world’s richest woman.

The wave of big money highlights the growing fear of a Mamdani win by many of New York’s wealthy and national conservatives. A self-described Democratic socialist, Mamdani’s platform includes a rent freeze, free buses, free childcare for all and government-run grocery stores. To pay for the programs, he’s proposed an additional 2% tax on New Yorkers who make more than $1 million a year.

Even as Mamdani maintains a double-digit lead in most of the polls, a vast money machine built on several pro-Cuomo PACs has gained steam as Election Day nears. Fix the City is by far the largest of the so-called “independent expenditure committees,” political fundraising groups akin to super PACs that can accept unlimited funds and were created to get around the new York City’s campaign finance limits. They are not tax deductible to the donors and are not permitted to coordinate their efforts with a specific candidate’s campaign.

According to filings, Fix the City has raised over $32 million, with many large gifts coming after Mamdani’s primary win in June. Two other anti-Mamdani committees include Defend NYC, which has raised $2.5 million, and New Yorkers for a Better Future, which has raised $1.5 million.

A PAC supporting Mamdani, called New Yorkers for Lower Costs, has raised just under $2 million. The only known wealth donor to contribute to that special committee is Elizabeth Simons, the daughter of the late billionaire hedge fund investor James Simons.

Many of the largest donations to Fix the City came before the primary, including two gifts in June from Michael Bloomberg totaling $8.3 million. Bloomberg, who met with Mamdani in September to offer advice, has not made any donations to the group since.

Many billionaires have ramped up their giving after the primary. Joe Gebbia, co-founder of Airbnb, Tesla board member and White House chief design officer, gave two gifts of $1 million each to two pro-Cuomo PACs in October.

Gebbia declined to comment on the gifts, as did several other billionaires mentioned in this piece. Others could not be reached for comment. 

The Lauder family, heirs to the Estee Lauder fortune, have given over $2 million to anti-Mamdani committees.  Ronald Lauder gave $750,000 to Fix the City in September, while William Lauder, chair of The Estee Lauder Companies, gave $500,000 in late August. Other members of the Lauder family have given more than $750,000 combined since June.

More than a half dozen members of the Tisch family, whose fortune stretches from real estate and hospitality to energy, packaging and sports, have given to Fix the City. Abigail, Louise, Maude and Laurie Tisch each gave $100,000 in October, while Alice Tisch gave $500,000. Elizabeth, Jonathan and Merryl Tisch also donated to the PAC after the primary. 

The Tisch family donations carry added symbolism since since Jessica Tisch, daughter of Loews Corp. CEO James Tisch, is the popular New York City police commissioner who has overseen a continued drop in crime in the city. Mamdani has said he plans to keep Tisch in her role as commissioner but has also called for an overhaul of policing and a new “department of public safety.”  

Many of the large donors backing Cuomo are hedge funders. Bill Ackman, who supported President Donald Trump’s re-election last year, gave $250,000 to Fix the City in October, following two gifts of $250,000 each before the primary. Dan Loeb of Third Point gave $100,000 in October after a $100,000 donation in June.

Some of the larger donors appear to have only loose ties to New York City.

Steve Wynn, the longtime Republican donor who listed his address as Las Vegas, gave $500,000 to Fix the City in October. Alice Walton, the world’s richest woman, listed her address as a post office box in Bentonville, Arkansas — Walmart’s hometown — when she made a $100,000 donation in August, on top of a $100,000 donation in April. Walton has little history of political giving in New York, beyond donating to pro-charter school groups and candidates. Mamdani has said he opposes the expansion of charter schools.

While many of the anti-Mamdani billionaires are Republicans, a notable exception is Barry Diller, the chairman of IAC and longtime New York philanthropist who’s giving has typically leaned toward Democrats. Diller gave $500,000 to Fix the City across two donations, with the most recent in October.

The worry by some pro-Cuomo supporters is that the giving by billionaires and the family dynasties could backfire in an increasingly populist political climate. Mamdani has made the donations a point of pride on the campaign trail, saying the spending by the rich is proof that his policies would restore power to everyday New Yorkers.

“They’re spending more money than I would even tax them,” Mamdani said in an interview with MSNBC Tuesday.