Just a handful of companies control the US seed market.
There's an age-old tradition in Washington of making unpopular announcements when no one's listening—like, you know, the days leading up to Thanksgiving. That's when the Obama administration sneaked a tasty dish to the genetically modified seed/pesticide industry.
This treat involves the unceremonious end of the Department of Justice's antitrust investigation into possible anticompetitive practices in the US seed market, which it had begun in January 2010. It's not hard to see why DOJ would take a look. For the the crops that cover the bulk of US farmland like corn, soy, and cotton, the seed trade is essentially dominated by five companies: Monsanto, DuPont, Syngenta, Bayer, and Dow. And a single company, Monsanto, supplies nearly all genetically modified traits now so commonly used in those crops, which it licenses to its rivals for sale in their own seeds.
What's harder to figure out is why the DOJ ended the investigation without taking any action—and did so with a near-complete lack of public information. The DOJ didn't even see fit to mark the investigation's end with a press release. News of it emerged from a brief item Monsanto itself issued the Friday before Thanksgiving, declaring it had "received written notification" from the DOJ antitrust division that it had ended its investigation "without taking any enforcement action."