As the month of September draws to a close, some stocks have thrived, while others have fallen. But as investors, it's not so much the actual gain or loss that matters the most -- although it certainly matters somewhat -- but rather what drove that movement. This month the worst-performing tech stock on the Dow Jones Industrial Average (DJINDICES:^DJI) was semiconductor powerhouse Intel (NASDAQ:INTC), whose stock had retreated some 10% over the last 30 days at the time of recording. Watch on to see what drove Intel's nosedive this month.