NEW YORK ( TheStreet) -- WPX Energy ( WPX) was the worst-performing stock in the S&P 500 on Monday morning. The S&P 500 was slipping nearly 4 points, or 0.28%, to 1358 in early trades. Shares of the Tulsa, Okla.- based oil and natural gas exploration company were down nearly 5% to $15.43 after Barclays lowered its rating on the stock to equal weight from overweight. The firm also dropped its 12-month price target by 21% to $19 from $24. WPX Energy currently trades at an estimated price-to-earnings ratio for next year of 42.58 times; the average among its peers is 25.5X. For comparison, EOG Resources ( EOG) has a lower forward P/E of 21.1X. Five of the nine analysts who cover WPX Energy rate it at hold. Three analysts have a buy rating and one is at sell. The stock has fallen 15.19% year to date.