Citi analyst Christian Wetherbee recommends using the selloff today in shares of CSX (CSX) as a buying opportunity. At Canadian Cacific (CP), Hunter Harrison needed 18 months to do the heavy lifting on the company's operational turnaround, Wetherbee tells investors in a research note. Harrison has worked for 10 months at CSX before his medical leave and the question is whether that is enough to successfully pass the reigns to Jim Foote to execute his vision, Wetherbee contends. Most of what needed to be done at CSX has already been done, the analyst contends, pointing out that CSX was in a better place than CP was in 2012 what Harrison took over. Wetherbee still thinks fair value for CSX shares is in the upper $50s excluding tax benefits, and upper $60s with tax reform. He keeps a Buy rating on the stock with a $58 price target. CSX is down 8%, or $4.34, to $52.97 in morning trading.