Mergers and acquisitions activity is booming. The record levels of 2017 have already been outstripped so far in 2018. With broader financial markets becoming distinctly jittery, not only those who remember the heady, pre-crisis days of 2007 are questioning whether the M&A market is riding for a fall — or checks and balances in the system are working better this time.

There are definitely warning flags. Valuations in certain sectors are stretched. Money is still cheap but is becoming more expensive. And the very length of this M&A bull market — nine years and counting — suggests it is due a reversal.

Some of the mega-deals that have been announced, moreover, make questionable long-term sense. Comcast’s ￡37bn acquisition of Sky, or Walmart’s $16bn purchase of Flipkart, look less like examples of visionary thinking than attempts to respond to disruptive domestic challengers by buying themselves out of obsolescence.