When Arabella Advisors announced on November 17, 2025 that its fiscal sponsorship business was being “acquired” by a newly formed public benefit corporation called Sunflower Services, the for-profit consultancy that had become synonymous with progressive dark money framed the transaction as a natural evolution. Five months later, the filings released alongside the announcement — and the operating patterns that have held steady since — tell a different story. The network that moved roughly $1.5 billion through four interlocking nonprofits in 2024 did not retire. It changed its letterhead.
The newest Form 990 filings, covering the 2024 tax year and posted to the Sixteen Thirty Fund’s own website in November 2025, document the single largest dark-money election cycle in the network’s history. Sixteen Thirty Fund alone reported roughly $282 million in revenue in 2024, after distributing more than $106 million in grants the previous year. Its 501(c)(3) sibling, the New Venture Fund, disclosed $887.4 million in gross receipts on its 2023 return and disbursed $592.9 million in grants that year — numbers that make it the largest single fiscal sponsor on the American left.
Anchored by those two vehicles, and joined by the Hopewell Fund and the Windward Fund, the Arabella-managed network moved approximately $1.5 billion in 2024 and spent $1.55 billion, according to an aggregate analysis of the filings compiled by CampaignNow and cross-checked against the Form 990s. That is more money than either major party’s national committee raised in the same cycle, routed almost entirely through nonprofits that are not required to disclose their donors.
The Pass-Through Machine
The mechanics that make the Arabella system work are, on paper, mundane. Each of the four nonprofit vehicles functions as a “fiscal sponsor,” meaning outside advocacy projects operate under the nonprofit’s legal and tax umbrella rather than incorporating separately. Those sponsored projects — there are hundreds — do not file their own Form 990s. Their income, spending, and grantmaking roll up into the parent’s return as undifferentiated line items.
The result, as the Capital Research Center has documented across a decade of filings, is a regulatory blind spot. A donor can write a check to the Sixteen Thirty Fund, earmark it for a project called “Demand Justice” or “Make It Work Action,” and the money appears on the Form 990 only as revenue to the parent entity. When that parent then grants money out — often to another Arabella-managed vehicle before reaching a visible recipient — the chain becomes functionally untraceable without access to internal accounting records that the IRS does not require to be disclosed.
- Sixteen Thirty Fund (501(c)(4)): $282 million in 2024 revenue; $23.7 million in reported federal political contributions, $37 million on ballot measures, $10.46 million in lobbying.
- New Venture Fund (501(c)(3)): $887.4 million in 2023 gross receipts; $592.9 million in grants; roughly $2.56 million in fees paid to Arabella Intermediate Holdings LLC that year.
- Hopewell Fund (501(c)(3)): the network’s secondary (c)(3), used for incubating newer projects and, per its filings, a recurring grantor to Sixteen Thirty.
- Windward Fund (501(c)(3)): the environmental-focused vehicle, responsible for a growing share of climate-advocacy grantmaking.
Sunflower Services, the new public benefit corporation that now provides finance, HR, grants management, and compliance services to those same four nonprofits, was financed by lead investor New Venture Fund, with additional capital from the Hopewell and Windward funds. In other words: the nonprofits that Arabella used to service pooled their own resources to purchase the servicing business from Arabella. The staff — roughly 240 professionals, led by former Arabella senior vice president Allan Williams — moved with the contracts.
Where the 2024 Money Went
The 2024 filings, combined with Federal Election Commission reports, establish what the Sixteen Thirty Fund did with its record-setting cycle. According to data maintained by OpenSecrets, Sixteen Thirty was a major donor to America Votes — the Left’s central turnout coordinating body — routing approximately $27.85 million there during the cycle. It sent $3 million on October 29, 2024 to Future Forward USA, the super PAC aligned with Vice President Kamala Harris’s presidential campaign, and additional sums to Civic Truth Action and similar independent-expenditure vehicles.
On the ballot-measure side, Sixteen Thirty spent $37 million across state campaigns focused primarily on abortion access, ranked-choice voting, and election-administration initiatives. Lobbying disclosures filed with the Senate Office of Public Records show $10,465,000 in federal lobbying spending in 2024 — a figure that rivals the combined lobbying budgets of some Fortune 100 trade associations. None of those expenditures require the donors funding them to be identified.
The pattern of recipient selection also bears on the “dark money” label that conservative watchdogs apply. Of the identifiable federal political contributions reported by Sixteen Thirty in 2024, effectively all flowed to Democratic candidates, Democratic-aligned super PACs, and left-of-center 501(c)(4) organizations. That is not, in itself, illegal or improper. But it underscores that the fund functions as a partisan election vehicle whose donors are shielded by the very tax structure that was designed to protect genuine social-welfare work from politicization.
Why the Rebrand Happened
The decision to spin off fiscal-sponsorship services into Sunflower, and the remaining operations into a separate company called Vital Impact, did not emerge from a strategic retreat. It emerged from sustained pressure. The House Ways and Means Committee had opened inquiries into fiscal-sponsor abuse of 501(c)(3) rules. State attorneys general — beginning with a coalition of Republican AGs in 2023 — had demanded documents on specific projects. The IRS had, as of 2025, flagged fiscal sponsorship as an area warranting updated guidance.
The Chronicle of Philanthropy reported in its November 18, 2025 account that the Arabella name had become “radioactive” with institutional donors, several of whom had quietly stopped renewing commitments. The New York Times reported in August 2025 that the Gates Foundation — cumulatively the network’s largest single funder with more than $450 million across sixteen years — had “quietly ceased backing” Arabella-affiliated organizations. With the brand damaged, the fiscal-sponsorship business was separated from the consulting arm, the operating team was moved under a new corporate parent owned by the nonprofits it serves, and the Arabella name was retired.
Critically, not a single underlying nonprofit dissolved. Not a single fiscally sponsored project closed. Not a single donor-advised fund was required to re-document its grantmaking. The Sixteen Thirty Fund’s 2024 Form 990, posted a week after the Sunflower announcement, lists the same executive director, the same board, the same program categories, and the same external counsel it listed in 2023. The change is cosmetic at the corporate-services layer and structural nowhere else.
The Precedent It Sets
What the Arabella-to-Sunflower transition demonstrates — beyond the specific scale of the network — is the durability of the fiscal-sponsor model against reputational damage. When a for-profit consulting firm becomes politically toxic, the underlying nonprofit architecture can absorb the shock by purchasing the services it used to buy, retaining the staff, and continuing operations under a new name. The donors, the grantees, and the regulatory treatment all stay where they were.
That model is not unique to the left. Conservative-aligned networks — including groups managed by DonorsTrust, and the constellation of 501(c)(4)s funded by the Koch network — operate on parallel principles, though at a smaller aggregate scale and with more visible donor identification in some channels. But the Arabella network’s 2024 filings, together with the post-rebrand continuity, offer the cleanest documentary record available of how a permanent, professionally staffed, billion-dollar-plus dark money system functions when it decides to keep functioning.
Capital Research Center senior research analyst Parker Thayer, speaking to The Center Square after the rebrand announcement, argued that the new structure was designed to “make the dark money funding trail more complex,” not to reform it. The filings released in the same month do not contradict that assessment. They show a network at its operational peak.
What to Watch
Several open questions will resolve over the next filing cycle. The first is whether Sunflower Services, as a public benefit corporation rather than a for-profit LLC, will disclose materially more information about its client mix and servicing fees than Arabella did. PBCs in Delaware, where Sunflower is incorporated, are required to produce a biennial benefit report but are not required to publish it, and early indications from the filing are that Sunflower intends to adhere to the minimum.
The second is whether the House Ways and Means Committee — which, as of early 2026, has continued its inquiry into fiscal-sponsor disclosure rules — will move on legislation requiring separate Form 990s for sponsored projects above a revenue threshold. Such a rule would not prohibit dark money flows but would make them considerably easier to trace. The third is whether any of the network’s major institutional funders beyond Gates have formally withdrawn; the Form 990 Schedule B, which lists top donors, remains redacted in the public disclosure copies. For now, the Arabella name is gone. The money, the staff, and the machinery remain.