There were notable absences, too. Indra K. Nooyi, the chief executive of PepsiCo, was invited but declined to attend. So too did Dinesh Paliwal, the head of Harman International. Even Mr. Jain’s cousin, Anshu Jain, the former co-chief executive of Deutsche Bank and now president of the brokerage firm Cantor Fitzgerald, passed on the evening.

(All those named above declined to comment or did not respond to a request for comment.)

Still, to those invited, Mr. Gupta’s presence at a dinner given by an executive of Mr. Jain’s stature was a sign that he was to be embraced by the pantheon of Indian business leaders in the United States.

It was a striking show of support, especially as Mr. Gupta had been convicted four years earlier of tipping off Mr. Rajaratnam to a crucial 2008 investment in Goldman Sachs made by Mr. Jain’s company, Berkshire Hathaway. Mr. Gupta was a director on the board of Goldman Sachs when Mr. Buffett poured $5 billion into the firm at the height of the financial crisis.

Mr. Gupta, the former global head of consulting giant McKinsey & Company, became a pariah among many of the corporate chieftains who once craved his counsel. Now 68, he has been trying to restore his reputation and rebuild his fortune since being released from a federal prison medical center in Devens, Mass.

But he has struggled to reconnect with many former associates and clients in the United States.

His ties to India’s business community, and its diaspora of executives in the United States, have proved more durable. Many of them, like Ajit Jain, go back many years. Both Mr. Jain and Mr. Gupta were graduates of India’s famed breeding ground for chief executives, the Indian Institute of Technology, and they had been close friends during their rise up their respective corporate ladders.