Uber, which is based in San Francisco, is also facing the consequences of its past behavior in overseas markets like London, its most profitable city. In September, regulators refused to renew Uber’s license to operate in the city, saying the company was not “fit and proper” to run a passenger transport service. Mr. Khosrowshahi publicly apologized, and the company has since made several changes sought by the city in the hope that the decision will be overturned on appeal as soon as next month.

Uber was much less accommodating in Southeast Asia.

The Competition and Consumer Commission of Singapore says Uber and Grab reneged on a promise to brief it fully on the details of the transaction before the deal was announced. (Uber says its lawyers provided an informal briefing a few days earlier.) The commission forced Uber to keep its app going until May 7, several weeks after the app was set to shut down, and barred Grab from raising prices for consumers or cutting payments to drivers while it considered whether to reverse or modify the transaction.

When antitrust regulators in the Philippines ordered the companies to maintain independent operations while they reviewed the deal, a top Uber executive in the region, Brooks Entwistle, responded at a public hearing: “Uber exited eight markets, including the Philippines, as of Monday. Now, I look after 10 markets, instead of 18. Our funding is gone. Our people are gone. We don’t intend to come back to these markets.”

That attitude did not impress Arsenio Balisacan, the chairman of the Philippine Competition Commission. “The acquisition results in a virtual monopoly of the ride-sharing market,” he said in an email. The commission has already seen prices rise and more driver cancellations of rides, resulting in poorer service, he said, adding that the agency was reviewing its options.

Malaysia and Vietnam are conducting their own antitrust inquiries.

In an interview, Uber’s No. 2 executive, Barney Harford, said the antitrust reviews in Southeast Asia were Grab’s problem.

“We are now a 27.5 percent shareholder in the combined entity,” Mr. Harford, the company’s chief operating officer, said in Mumbai last month. “That’s obviously not a controlling position, so the management team of the controlling entity are now on point for handling the regulatory questions.”