Stocks ended little changed yesterday, as investors await the outcome of a crucial meeting of European Central Bank officials early Thursday and the latest U.S. employment data on Friday. Productivity of the U.S. nonfarm business sector rose at a 2.2% annualized rate in the second quarter, stronger than the 1.6% pace estimated a month ago. Unit labor costs were revised lower, to a 1.5% annual increase from 1.7%. Facebook climbed almost 4.8% a day after Chief Executive Mark Zuckerberg said in a regulatory filing that he won’t sell any of his company’s stock for the next year. Advanced Micro Devices fell 3.57% after UBS cut its rating to neutral due to matters such as “a shrinking PC client serviceable market” and greater competition from its top rival, Intel. Nokia fell 15.9%, as the co. showed of its newest Lumia 920, running on Microsoft’s Windows Phone 8 operating system, at an event in New York.