Navistar’s board adopted a stockholder rights plan to fend off hostile bids. Hedge fund manager Mark Rachesky disclosed he controls a 13.6 percent stake. His former mentor, Carl Icahn, owns 11.9 percent. Shares have slid 25 percent this year after falling 35 percent in 2011. Also, the EPA is fining Navistar for shortcomings in pollution-control technology the agency helped it develop.