Jefferies analyst Brandon Couillard views the selloff in shares of Exact Sciences following the U.S. Preventive Services Task Force draft recommendation for colorectal cancer screening as overdone. In a departure from its former grade-based rating system, the panel deemed stool DNA testing, which is used by Exact's Cologuard, as a second tier "alternative" test, Couillard tells investors in a research note. While the pathway for private payor reimbursement may now be lower and slower for Cologuard, the initial after-hours selloff appears overdone, the analyst writes. He recommends buying shares of Exact Sciences on the open. "Considerable" short covering, which 27% of float sold short, should offer support for the stock, the analyst argues. He keeps a Buy rating on the Exact with a $35 price target. The stock is down 34%, or $6.25, to $12.28 in pre-market trading.