It's been a hot and cold year for the stock market, but these Fortune 500 companies managed to float to the top with impressive gains. From Ross Stores to MasterCard, here are the biggest winners.

From 30,000 feet, this year's volatile swings in the stock market don't look as bad, with the S&P 500 down only 3% for the year.

Centene Corp. (NYSE:CNC) announced it will present at the Citi 2011 Global Health Care Conference, to be held March 1-3, 2011, at the Hilton New York Hotel in New York City. Centene is scheduled to present on Tuesday, March 1st, at 11:00 AM Eastern Standard Time. A webcast replay will be available shortly after the presentation via the Company's website at www.centene.com.

American Video Teleconferencing Corp. (Pink Sheets:AVOT) is pleased to announce that it has hired a French speaking geologist to search the archives of the Quebec Department of Mines for Rare Earths showings not on a current computer file.

Orofino Gold Corp. (ORFG.PK) is a US (Nevada) company established for the purpose of creating a significant exploration and mining group to operate in Colombia.

Orofino has major criteria by which they select properties that includes:

* Significant historical production
* Favorable geology for hosting major ore bodies