I expect we will hear a lot more about this new report:

The political Left often criticizes—and the mainstream media frequently report on—the network of center-right nonprofits funded by billionaire entrepreneurs Charles and David Koch. But few politicos know of a left-wing leviathan in Washington, D.C., with a reach rivaling that of the Koch network.
This study by the Capital Research Center documents a shadowy web into which nearly $600 million flowed in 2017, the most recent year for which tax returns are available. Operating under the aegis of “philanthropy,” this network is housed in and staffed by a for-profit, privately held consultancy called Arabella Advisors, LLC.* Arabella manages four nonprofit entities—the New Venture Fund, Sixteen Thirty Fund, Windward Fund, and Hopewell Fund—each of which shares an address and interlocking officers with Arabella.