<span style="line-height: 20.8px;">More than $400 billion worth of corporate mergers have been withdrawn in the United States since the beginning of January &mdash; almost three times the previous record for the same period,&nbsp;</span><a href="http://www.nytimes.com/2016/05/12/business/dealbook/hedge-funds-look-for-hard-hats-in-a-year-of-collapsing-mergers.html?ref=dealbook" style="line-height: 20.8px;">Leslie Picker reports in DealBook</a>&nbsp;