In 2005, service to Asia was expanded as Continental introduced daily nonstop service between Newark and New Delhi, India. The success of this Newark-New Delhi route presaged establishment of a second gateway in India with the announcement of daily nonstop service to Mumbai. With the establishment of Mumbai service, Continental offers the most nonstop flights by any carrier from the United States to India. By May 2006, the carrier's passenger traffic surpassed that of Northwest Airlines, and Continental became the fourth-largest U.S. carrier. "The Wall Street Journal" reported on December 12, 2007 that Continental was in merger discussions with United Airlines. Of issue would be Continental's golden share held by Northwest Airlines and the divestiture of Continental's Guamanian hub. A deal was not "certain or imminent", with the talks being of a preliminary nature. In April 2008, at the height of oil prices, Northwest announced a merger with Delta Air Lines. This allowed Continental to buy back the golden share from Northwest Airlines, which it did. Continental then renewed merger talks with United Airlines, but broke them off again that same month. In May 2008, Continental Airlines sold its remaining 4.38 million share investment in Panamanian flag carrier Copa for $35.75 a share, netting proceeds of $149.8 million. Continental had been a principal shareholder in Copa. In June 2008, due to national and international economic conditions, Continental cut 3,000 jobs and the CEO and president had reduced salaries for the remainder of the year. The airline also reduced capacity and eliminated 67 mainline aircraft from its fleet by the end of 2009, retiring all of Continental's 737-300s and all but 35 of its 737-500s. Continental also announced that it planned to withdraw from the SkyTeam Alliance and would join the Star Alliance in order to cooperate more extensively with United Airlines and other Star Alliance airlines. The new Continental-United relationship has been characterized as a "virtual merger" in some circles. In September 2008, Continental announced that it would commence providing seasonal non-stop service between Houston and Rio de Janeiro. The new non-stop flight was timed to provide roundtrip flight connections at Continental's Houston hub to more than 160 cities throughout the U.S., Canada, Central America, Europe, and Asia. Continental renewed its lease for around in Continental Center I. Continental announced that its 4th quarter 2008 net loss widened to $266 million on costs for pilot retirement and reducing the value of its fuel hedges. In January 2009, Continental became the first commercial carrier to successfully demonstrate the use of sustainable biofuel to power an aircraft in North America.