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The 10 Worst S&P 500 Stocks in All of 2015

NEW YORK (TheStreet) -- A tumultuous third quarter didn't help stocks that were already turning big losses for the year.

Stocks took a nosedive in August fueled by investor concern regarding slowing growth in China. The continued precipitous decline in oil (and now other commodities too) as Wall Street continues to wait for the Fed to raise interest rates (which now looks like December) all contributed to choppy markets this year.

As a result of August's stock market selloff, the S&P 500 index had its worst quarterly performance in four years, slumping 6.9% for the three-months ending Sept. 30 and 6.7% for the year, despite Wednesday's market rally.

Here are the 10 worst-performing stocks in 2015, paired with TheStreet Ratings to let you know if you should buy or sell these stocks as we head into the final quarter of the year.

TheStreet Ratings uses a quantitative approach to rating over 4,300 stocks to predict return potential for the next year. The model is both objective, using elements such as volatility of past operating revenues, financial strength, and company cash flows, and subjective, including expected equities market returns, future interest rates, implied industry outlook and forecasted company earnings.

Buying an S&P 500 stock that...