NEW DELHI - Malvinder Mohan Singh has stepped down as chairman, managing director and chief executive of India’s largest pharmaceutical company, Ranbaxy Laboratories, which was acquired last year by Japan’s Daiichi Sankyo.

Atul Sobti, the current chief operating officer, has been appointed chief executive and managing director, while Tsutomu Une, the company’s non-executive director, will serve as its chairman, a company statement said Sunday.

“We very much appreciate the efforts of the Singh family, which grew Ranbaxy from a small, local Indian company to the large multi-national company it has become today,” said Takashi Shoda, a director at Ranbaxy and the chief executive of Daiichi Sankyo.

Malvinder Singh said he was stepping down as the acquisition of his company was complete. “It was a difficult decision to separate from Ranbaxy,” he said, adding: “But it was the right time for me to do so.”

The Singh family had earned some Rs.100 billion ($2.4 billion) from selling their 34.82 percent stake last June in the pharmaceutical major, valued at around Rs.100 billion.

Daiichi Sankyo, which subsequently made an offer for a further stake hike, currently owns 63.92 percent in Ranbaxy, which has customers in 125 countries, an expanding international portfolio of affiliates, joint ventures and alliances in 49 countries and manufacturing operations in 11 countries.

Soon after the stake sale mid-2008, Singh had said he would invest in Religare and Fortis, the family’s financial service and healthcare companies.

“Healthcare and financial services are two areas where we have existing businesses, where we will make investments,” Singh had announced at a press conference, adding that he also planned to list diagnostics subsidiary SRL Ranbaxy.

“I think for the next many years, our focus is clear: to remain in healthcare and to make it number one healthcare firm in India.”

Singh has also made it clear he planned to take Fortis globally. “We will first have a strong presence in Asia and then will take it to other markets. That will happen in a phased manner.”

Similarly, he said efforts would be made to make Religare a leader in the financial service sector, conceding that funds from the stake sale would be utilised by Fortis and Religare for mergers and acquisitions. “It is an integral part of the growth of these companies.”

The change in management at the company announced Sunday comes at a time when it has reported a net loss of Rs.1,044.8 crore ($204 million) for 2008 against a net profit of Rs.617.7 crore in the previous year.

The company has also been in trouble with the US Food and Drug Administration over alleged falsification of test results in approved and pending drug applications.