AT&T rocked the tech world this week, when it announced its plans to acquire T-Mobile for a combination of stock and cash valued at around $39 billion, making what will likely be the biggest mobile news of CTIA week before the event even kicked off. The first question of pundits everywhere, naturally, was what manner of antitrust issues would arise with such an acquisition.

After all, AT&T and T-Mobile are two of the largest operators in the telecom space, and such a deal could potentially mark a big blow against competition, as the big four wireless carriers in the U.S. shrink down to three. AT&T did its part to answer these concerns before they were even raised, noting in its press release, “The U.S. wireless industry is one of the most fiercely competitive markets in the world and will remain so after this deal. The U.S. is one of the few countries in the world where a large majority of consumers can choose from five or more wireless providers in their local market.”

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AT&T CTO Randall Stephenson also sought to curb governmental fears by insisting that such a deal “represents a major commitment to strengthen and expand critical infrastructure for our nation’s future. It will improve network quality, and it will bring advanced LTE capabilities to more than 294 million people.”

AT&T was right to be concerned, of course. The history of tech mergers and acquisitions has been dotted with government investigations, which can often tie up deals for years on end. Given how much of a stake AT&T and T-Mobile have in the U.S. wireless market, we’re likely to see intense scrutiny of the deal at the hands of governmental bodies.

In this slideshow, we take a look at some of the more notable mergers and acquisitions that have taken place in recent decades. The deals run the gamut from fiscally sound to downright economic train wrecks.