
Market swoons are bad news for dealmakers. Stock-market plunges can erode the value of bids involving acquirers’ stock, make bankers reluctant to lend, and change the outlook violently. Recent market tumult, with the S&P 500 Index down 6 percent last week, doesn’t qualify as an extinction event – at least not yet. It does, however, make it harder to overlook regulatory dangers attached to certain possible deals, like the combinations of CVS Health and Aetna and AT&T and Time Warner. Last year was the fourth in a row with over $1 trillion of announced transactions involving U.S. companies worth over