NEW YORK ( TheStreet) -- Second-quarter earnings, and economic data from China and the U.S. will be key triggers to stock rating changes during the second half. Concerns related to the pace of the global economic recovery and the offsetting effect of bargaining opportunities in metal stocks could keep recommendations relatively bullish for the remainder of 2010.Analysts have turned bullish on the metal stocks, especially copper, during the past six months. During the first quarter, a boost in demand for base metals on the global economic recovery pushed up metals prices, thereby increasing the profitability of the metal producers. During the second quarter, prices slumped on headwinds blowing from the eurozone and from monetary tightening in China. Despite subsequent selloffs, analysts reckon fundamentals remain positive and metal stocks offer attractive bargaining opportunities. Copper Stocks Over the past six months, analysts have been more bullish on Southern Copper ( SCCO) than Freeport-McMoRan Copper & Gold ( FCX) and Teck Resources ( TCK). Analysts favored Southern Copper primarily because of its large reserve base. The capital expenditure plan, defined earlier this year, provided Southern Copper the opportunity to expand production over 2009. Based on the positive demand trends for copper during the first quarter, analysts expected Southern Copper to report higher revenue than Freeport and Teck Resources. Hence, Southern Copper received higher upgrades than the other two copper majors. In addition, Southern Copper has a lower cash cost profile for new projects vis-a-vis industry peers. Analysts turned bullish on copper stocks during the first quarter of 2010, buoyed by the positive sentiment in global markets. Despite copper for spot delivery on the London Metal Exchange correcting 12% during the second quarter, analysts continue to be bullish on stocks as they reckon the stock price corrections are overdone. During the second half, the biggest triggers for a downside rating change for copper stocks could be major decline in China copper imports and consumption, and U.S. housing data. Aluminum Stocks An interesting upgrade in analyst recommendations was observed for aluminum stocks. Alcoa ( AA) received upgrades only during the first quarter, while ratings remained unchanged during the second quarter.