Computer Sciences Corp., a technology contractor for governments and companies, fell after saying it will write down its investment in a U.K. contract by as much as $1.5 billion as the agreement is being renegotiated. CSC, based in Falls Church, Virginia, declined 9 percent to $24.10 at the close in New York, the most since Nov. 10. It has lost 51 percent this year. Moody’s Investors Service placed all CSC ratings under review for possible downgrade. The company will revise its forecasts for fiscal 2012 and book a “material impairment’’ in the third quarter ending this month that could total all of the $1.5 billion it has spent on a U.K. electronic patient-records contract, according to a regulatory filing.