12:30 PM New York – MercadoLibre, the online e-commerce site operator plunged 9%. Pacific Ethanol surged 60% on the expectations of higher sales. McMoran Exploration soared after it discovered energy prospects in the Gulf of Mexico.

Of the stocks in S&P 500 index, 320 increased, 172 declined and 8 were unchanged.

Northern Trust Corporation led the decliners in the S&P 500 index with a loss of 2.7% followed by losses in Eastman Kodak Company of 2.7% and in Avon Products, Inc of 2.6%, in Apollo Group, Inc of 2.2% and in Nabors Industries Limited of 2.1%.

Corning Incorporated led gainers in the S&P 500 index with a rise of 4.1% followed by gains in Janus Capital Group Inc 3.3%, in United Parcel Service, Inc of 3.0% and in Allegheny Technologies Incorporated 2.9%.

Other Movers

Alcoa Inc (AA) the aluminum producer advanced 1.8% or 31 cents to $17.33.

Allscripts-Misys Healthcare Solutions, Inc (MDRX) added 1.5% or 31 cents to $20.10 after the provider of health care information technology reported second quarter revenues rose 31.6% to $169.3 million from $128.6 million a year ago. Net income in the quarter was $15.8 million or 10 cents per diluted share compared to net loss of $6.0 million or 5 cents per share a year ago.

Aluminum Corporation of China Limited (ACH) the producer of the metal added 5.0% or $1.63 to $34.00.

Associated Banc-Corp (ASBC) decreased 5.1% or 64 cents to $11.70 after the regional bank reported fourth quarter net interest income fell 7% to $178.4 million from $191.8 million a year ago. Net loss in the quarter was $180.6 million or $1.41 per diluted share compared to net income of $13.6 million or 11 cents per share a year ago.

Berry Petroleum Company (BRY) declined 5.5% to $29.20 after it agreed to pay $126 million to acquire interests in producing properties in West Texas with 11.2 million barrels of oil equivalent. The company also increased its 2010 capital budget by $30 million to between $250 million and $290 million and drill 27 properties on Permian property.

Citigroup Inc (C) rose 0.8% or 3 cents to $3.62 ahead of earnings from banks in the next two weeks.

Corning Incorporated (GLW) gained 2.5% or 51 cents to $20.40 after the maker of glass for liquid-crystal displays was upgraded to “buy” from “hold” at Deutsche Bank AG.

Daimler AG (DAI) the maker of Mercedes-Benz added 1.4% or 78 cents to $54.16 after the comments from German auto industry group head suggested higher sales for Mercedes Benz in U.S.

Fomento Económico Mexicano, S.A.B. de C.V (FMX) plunged 11.7% or $5.83 to $43.94 after the Mexico based brewer agreed to be acquired by Heineken NV for $7.7 billion in an all share deal.

Helen of Troy Limited (HELE) fell 2.6% or 65 cents to $24.06 after the personal-care products maker reported third quarter sales rose 2% to $189.4 million from $185.6 million a year ago. Net income in the quarter rose 63.6% to $24.7 million or 80 cents per diluted share compared to net income of $15.1 million or 48 cents per share a year ago.

Hughes Communications, Inc (HUGH) the provider of broadband satellite network services and systems rose 7.3% or $1.85 to $27.12 on media speculation.

McAfee, Inc (MFE) advanced 1.6% or 64 cents to $40.52 after the maker of security software was upgraded to “buy” from “neutral” at UBS AG.

McMoran Exploration Co. (MMR) surged 37% to $12.59 after it said it discovered hydrocarbon prospects at on its Davy Jones ultra-deep prospect located on South Marsh Island Block 230 in approximately 20 feet of water. The company plans to drill 29,000 feet to test the energy prospects.

Mercado Libre, Inc (MELI) declined 8.6% to $46.15 after the online market place company focused on Latin America on a sharply higher volume of 2.25 million shares and the stock was downgraded by JP Morgan to “neutral” last week.

Pacific Ethanol Inc surged more than 60% as retail investors purchase renewable energy stocks. The company announced last week that it will restart production at one of its ethanol facilities.