The Journal originally reported that Model S sales had declined 26 percent in September, and that caused the TSLA drop. Later, there was the clarification that this only refered to US sales, but it wasn't until Musk Tweeted that the, "Article in WSJ re Tesla sales is incorrect. September was a record high WW (worldwide) and up 65% year-over-year in North America" that things on the Tesla stock front really picked back up.
Questions remain about Tesla's actual production and sales numbers. Unlike many other automakers, Tesla doesn't release monthly sales figures but it does talk about quarterly figures in investor calls every three months. During the last call in July, Tesla said it had delivered 7,579 Model S EVs in the second quarter of 2014 (the most ever delivered in a quarter) and said it remained, "on track for more than 35,000 deliveries in 2014." This target was questioned by analysts, which led to the Journal piece, and then the response Tweet. We don't know what'll happen with the stock today, but we will know the company's official delivery numbers when Tesla issues its Q3 2014 Financial Results after the close of trading on Wednesday, November 5.