The S&P 500 Index (SNPINDEX:^GSPC) rose 3.5 points, or 0.23%, today to close the week at 1,518. Despite Friday's moderately higher market, these three S&P 500 components were thoroughly disappointing, ranking as the worst performers in the index.

Sometimes, the day's laggards are unfamiliar sights, falling on a negative rumor or as a result of some political agenda that's briefly in the headlines. Not the case with Peabody Energy (NYSE:BTU), which fell 4.6% today. The consistently underperforming coal miner has lost more than 20% in 2013, and 40% in the last year. With the rise of cleaner energies like natural gas, "dirty coal" has lost popularity. Today's stumble was the result of an analyst citing the potential for Chinese coal demand to wane as the country fights pollution.

GameStop (NYSE:GME), set to report earnings later this month, dropped 4% today. The main reason for Friday's decline was because the stock went "ex-dividend" today, meaning that anyone listed as holding the stock as of today will receive the next quarterly dividend. Some short-term investors will hold stocks until their ex-dividend date to make sure they'll receive the next dividend, then sell immediately. With a 4.4% annual dividend, GameStop's payout isn't exactly trivial. 

Finally, shares of semiconductor producer Advanced Micro Devices (NASDAQ:AMD) slipped 2.8%. Apparently, AMD settled a lawsuit from Tessera Technologies, one that dates back to 2005, in which Tessera claims AMD infringed on patents in some of its products. Although exact details of the resolution weren't released, the news that AMD will be shelling out money at a time it needs to be investing in itself doesn't exactly make for happy shareholders. The stock is down nearly 70% in the last year alone, as the business struggles to adjust to a rapidly evolving technological landscape.