Microsoft Corp. is planning its biggest round of job cuts in five years, as the software maker looks to slim down and integrate Nokia Oyj’s handset unit, people with knowledge of the company’s plans said. “The reductions, which may be unveiled as soon as this week, will probably be in areas such as Nokia and the parts of Microsoft that overlap with that business, as well as marketing and engineering,” said the people who asked not to be identified because the plans aren’t public. “The restructuring may end up being the biggest in Microsoft history, topping the 5,800 jobs cut in 2009,” two of the people said. “Some details are still being worked out,” two of the people said. The announcement would come one week after chief executive officer Satya Nadella issued his first company mission statement, calling for greater emphasis on mobile devices, cloud-computing and productivity software.