Vanguard, the world's second-largest asset manager, increased exposure to large bank's bonds during the banking rout in March, taking advantage of cheap valuations, according to a report seen by Reuters. The collapse of two U.S. regional banks last month triggered wild price fluctuations across fixed income markets, with worries over the banking sector weighing broadly on corporate bond prices. "The banking troubles offered a brief window to add large banks at compelling valuations," said the report, written by Sara Devereux, global head of fixed income group, and her team.