Facebook’s planned purchase of a startup called Kustomer is the kind of deal that would barely have raised an eyebrow among antitrust regulators a few years ago. The company is small and sells customer service software, far outside Facebook’s core social media and virtual reality businesses. But now that U.S. regulators are attempting to unwind two of Facebook’s past marquee acquisitions, they are scrutinizing even minor deals struck by the company.

In mid-February, the Federal Trade Commission opened an in-depth investigation of Facebook's $1 billion takeover of Kustomer, a deal announced in late November, according to two people with direct knowledge of the situation. This process, which only happens in a small fraction of mergers, is a sign of how the government is increasingly scrutinizing deals between companies that don’t directly compete. In this case, the review could trigger more issues: Companies that compete with Kustomer in selling customer relationship management software gave The Information some indication they might formally object to the deal.