CSX shares derail after CEO takes unexpected medical leave

CSX Corpshares skidded as much as 10 percent on Friday, wiping out $4 billion in market value, as the No. 3 U.S. railroad by revenue sought to assure investors its turnaround would progress despite the unexpected medical leave of its chief executive officer.CSX stock, which has soared nearly 60 percent this year, tumbled 7.3 percent to $53.11 in midafternoon trading after earlier falling as low as $51.63.Most of the gains came after Hunter Harrison, 73, who led turnarounds of two Canadian railro