A) The entire market has rolled-over and I suspect it has something to do with the expected outcome of the vote in Congress on whether to strike Syria.
B) On a technical basis TSLA is over extended. For chartist a double-top occurred today and TSLA was unable to maintain a price of $173 which was its high on 8-26.
C) Based on fundamentals TSLA is over-valued. You can use a price to sales ratio and even when compared to a PS for a technology company TSLA is currently expensive.
D) No stock goes up forever. Apple went from over 700 to under 500, Amazon went from over 50 to around 7, Netflix went from over 300 to below 70, Deckers went from 118 to below 40.