Three years and more than $3 trillion worth of megadeals later, investors may well wonder if bigger is better. Shares of Boston Scientific Corp. spiked 7.4 percent on Monday after the Wall Street Journal reported that fellow medical-device maker Stryker Corp. had offered to acquire it. Its unclear how Boston Scientific feels about a deal, if in fact theres one on offer. Following the report, shares of both companies were halted for "news" that ended up being a Boston Scientific statement acknowledging the story and saying it doesnt comment on speculation. Cool. On average, analysts estimate Boston Scientific could command $39 a share in a takeover, implying an almost $60 billion deal including debt. Amazingly, that would be only the third-biggest acquisition announced this year, trailing Takeda Pharmaceutical Co.s $80 billion bid for Shire Plc and Cigna Corp.s nearly $70 billion purchase of Express Scripts Holding Co. All in, there have been 20 megadeals ($10 billion-plus) in 2018. This flurry of outsize dealmaking has generally been predicated on the idea that scale is needed to offset shrinking margins as business models are upended by new entrants and digital strategies. A Boston Scientific-Stryker tie-up would be a prime example. Its essentially a bet that bigger medical-device makers have more negotiating power with hospitals and are better positioned for a consolidating health-care environment. AT&T Inc.s $109 billion purchase of Time Warner Inc. rests on similar logic. The weaknesses these deals are trying to shield are real, but megamergers arent always the fix theyre designed to be. Bigness can stifle innovation. In the medical-device industry, Medtronic Plcs $53 billion takeover of Covidien in 2015 should be flashing even bigger warning signs for Stryker. The deal was a tax inversion, but those benefits have faded in the wake of the new US legislation. In fact, it’s kind of been a dud. Medtronic has noted that a broad bundling of products for hospitals isnt really a thing yet, while Stryker and Boston Scientific have actually talked up the importance of focusing on fast-growing niches rather than sheer size, says Jefferies analyst Raj Denhoy. Whats most interesting to me is that people like Denhoy are willing to be skeptical about the merits of a megacombination. That was rarely the case in the heyday of 2015. You also see this from investors. Stryker shares fell about 5 percent on Monday and continued their decline Tuesday. Comcast Corp. has taken a beating amid speculation that it could try to disrupt Walt Disney Co.s $66 billion acquisition of 21st Century Fox assets. As my colleague Tara Lachapelle notes, it doesn’t really matter what Comcast shareholders think, but elsewhere, investors may start forcing companies to come up with a more creative solution than a megamerger for their weak spots. Bloomberg View