Margaret Anne Cargill. Image via Wikipedia  The Chronicle of Philanthropy’s annual list of America’s 50 most generous donors is out, and the name at the top will surprise you.  Margaret Cargill beat out big-name billionaire philanthropists including George Soros, Michael Bloomberg and Paul Allen for the #1 spot. Not only is she almost entirely unknown, but the heiress to the Cargill agribusiness fortune passed away in 2006.  Her family’s company isn’t exactly a household name either, despite topping Forbes’ list of America’s Largest Private Companies almost every year since the chart’s 1986 debut.  Between 1998 and 2011, Cargill has been #1 every year but two (in 2006 and 2007, billionaire-owned Koch Industries won out). The Minnesota-based food, agriculture and fertilizer conglomerate saw its revenues top $109 billion last year.  So why is Margaret just hitting the list now with her $6 billion bequest? The Chronicle explains her somewhat complicated estate planning arrangements as follows:  Ms. Cargill, who was 85 when she died in 2006, left all of her shares of Cargill stock to be split between the Anne Ray Charitable Trust and the Margaret A. Cargill Foundation, in Eden Prairie, Minn. The amount the two nonprofits are set to receive from the bequest totals roughly $6-billion, but the way the payout is structured is complex.  Because Cargill remains a privately held company, officials at the foundation and the trust could not at first liquidate the private Cargill stock. But that changed last year when the conglomerate sold its 64-percent stake in a publicly traded business called the Mosaic Company. Once the company sold its stake in Mosaic, officials at the nonprofits were able to exchange the private Cargill stock for public Mosaic stock. Under this arrangement, the foundations ended up with about 114.5 million shares of Mosaic stock, which will eventually provide at least $6-billion to the trust and foundation.  To receive some of the bequest money right away, foundation officials last year sold 49.5 million of the Mosaic shares for a total of about $2.8-billion. The nonprofits still own about 65 million Mosaic shares but are not allowed to sell them until May 2013. When the sale of those shares is completed, the philanthropies Ms. Cargill established could become two of the wealthiest grant makers in the United States.  Margaret isn’t the only Cargill to remain well under the radar. Last year, my colleague Brian Solomon put together a family tree in an effort to break down their fortune. As you can see from Forbes’ illustration, Margaret never had any children, and left her entire fortune to charity.  Follow me on Twitter at @Clare_OC or subscribe on Facebook.
The Chronicle of Philanthropy just released its list of the most generous donors of 2011. The top spot goes to a woman you've never heard of who died years ago.