NEW YORK ( TheStreet) -- SAIC ( SAI) was the worst-performing stock in the S&P 500 intraday Monday. The S&P 500 was falling less than 1 point, or 0.01%, to 1,342. Shares of SAIC decline 5.07% to $11.62. The company lost a Department of Defense contract to Lockheed Martin ( LMT) on Friday, Bloomberg reported. The contract was SAIC's largest, generating revenue of $400 million, according to Stifel Nicolaus analysts, said Bloomberg. SAIC trades at an estimated price-to-earnings ratio for next year of 9.13 times; the average among its peers is 14.73. For comparison, IBM ( IBM) has a higher forward P/E of 14.37. Nine of the 16 analysts who cover SAIC rated it hold. Six analysts gave the stock a buy rating and one rated it sell. The stock has fallen 5.45% year to date.