Morning Market Losers

Amkor Technology (NASDAQ: AMKR) shares slipped 16.42% to $6.26 after the company reported weaker-than-expected Q3 results and issued a downbeat Q4 forecast.Twitter (NYSE: TWTR) shares declined 12.99% to $42.25. Twitter met Wall Street's earnings expectations. The company issued a weak revenue forecast for the fourth quarter. In the latest period, Twitter's user base grew 23% to 284 million. Analysts at Nomura downgraded Twitter from Buy to Neutral and lowered the price target from $55.00 to $45.00.Ducommun (NYSE: DCO) shares fell 12.84% to $25.12 after the company reported Q3 earnings of $0.24 per share on revenue of $188.20 million.PRGX Global (NASDAQ: PRGX) shares tumbled 12.41% to $5.20 after the company reported a loss in the third quarter.Luminex (NASDAQ: LMNX) shares dropped 12.33% to $18.25 after the company reported Q3 earnings of $0.27 per share on revenue of $56.70 million.Medidata Solutions (NASDAQ: MDSO) shares declined 10.07% to $38.74 after the company reported Q3 earnings of $0.20 per share on revenue of $86.0 million. The company also lowered its FY14 guidance.Kohl's (NYSE: KSS) shares slipped 6.30% to $54.86 after the company issued a weak guidance on Monday. The company projected comparable sales to drop by 1.4% in the third quarter. It also expected 2014 diluted earnings on an EPS basis to be at the low end of previous forecast.CommVault Systems (NASDAQ: CVLT) shares dropped 5.07% to $41.49 after the company reported downbeat quarterly results.