Yahoo could be gearing up for its biggest layoff ever. All Things D says new CEO  Scott Thompson is working on a reorganization that could hit the company's products organization, PR and marketing, research, and regional efforts. Writes Kara Swisher:

In Yahoo’s core business, Thompson appears to be looking widely across Yahoo in order to jumpstart what has largely been a failed turnaround for the company under previous leadership. That is likely to include a much deeper and significant paring of its many businesses, while also seeking out new ones to move into.

One manager said cuts will be "deep," and that units will have to demonstrate either substantial savings or clear paths to higher revenue. Meanwhile, an independent source tells me that a number of Yahoo managers are exiting or looking for new opportunities. The company's media business may be left largely alone for now, notes Jeff Bercovici at Forbes. Media's not on Swisher's list of possible targets, and the company's "reportedly angling to secure the rights to broadcast the 2014 Winter Olympics and 2016 Summer Olympics in Canada," Bercovici. The layoffs could be announced late this month. Updated 2:30 to add information from independent source.