Barclays PLC began laying off 3% of its global investment banking staff this week, targeting 3% of its global investment banking workforce, people familiar with the matter said on Wednesday. Barclays has sought to streamline its operations after a tumultuous year. The cuts are part of an annual review that also involves deals and research, the sources said. Overall, up to 300 employees could lose their positions in this round of layoffs, the sources added.