Based on the data in the PDF the average global M&A volume over the past 6 months (an arbitrarily chosen period) has been (312.17 + 391.33 + 290.01 + 202.21 + 304.50 + 253.91) / 6 which works out to around $292.36 billion. To get more than the $839 billion indicated in the question would require an average of about $279.67 billion per month.
The total for April according to the link is $253.91 billion. This means that at least another (839 - 253.91) / 2 or $292.55 billion is needed per month on average for the question to resolve as a yes. I've been under the assumption that the question will resolve as a yes if this year's second quarter volume is more than $839 billion but I'm not so sure anymore (will Reuters report revised figures for 2016 when the question resolves?).
It looks like April wasn't very good: https://www.paulweiss.com/practices/transactional/mergers-acquisitions/publications/ma-at-a-glance-may-2017?id=24330
Based on the data in the PDF the average global M&A volume over the past 6 months (an arbitrarily chosen period) has been (312.17 + 391.33 + 290.01 + 202.21 + 304.50 + 253.91) / 6 which works out to around $292.36 billion. To get more than the $839 billion indicated in the question would require an average of about $279.67 billion per month.
The total for April according to the link is $253.91 billion. This means that at least another (839 - 253.91) / 2 or $292.55 billion is needed per month on average for the question to resolve as a yes. I've been under the assumption that the question will resolve as a yes if this year's second quarter volume is more than $839 billion but I'm not so sure anymore (will Reuters report revised figures for 2016 when the question resolves?).