On Tuesday, the GovCon Index will replace ATK and Orbital Sciences with Orbital ATK (NYSE: OA), the company formed out of the merger of ATK’s aerospace and defense groups with Orbital.
Shipbuilding giant Huntington Ingalls (NYSE: HII) will also join the GovCon Index on Tuesday to maintain the index’s number of companies at 30.
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U.S. stocks declined on new of an impasse between Greece and the European Commission on how to resolve the country’s debt situation and a report that showed year-over-year declines on China’s imports and exports, according to Reuters.
The Dow Jones Industrial Average dipped 95.14 points to 17, 729.15, the S&P 500 composite index declined 8.76 points to 2, 046.71 and the NASDAQ composite index fell 18.39 points to 4, 726.01.
Top Percentage Gainers
 Company |  Stock Price |  $ Change |  % Change |
 Serco Inc. |   3.025 |   0.23 |   8.23% |
 Engility Holdings |   47.65 |   1.15 |   2.47% |
 Orbital |   28.85 |   0.21 |   0.73% |
  ATK |   140.03 |   0.78 |   0.56% |
  Northrop Grumman |   162.97 |   0.73 |   0.45% |
Market Summary
 Advancing Issues |   8 (26.66%) |
 Declining Issues |  22 (73.33%) |
 Unchanged Issues |   0 |
Executive Mosaic‘s GovCon Index is a composite index that tracks 30 of the largest publicly-traded Government Contracting (GovCon) firms.