Tesla shares are down in premarket trading Thursday as more disappointing sales data is dragging on the stock along with the lackluster second-quarter earnings report Tesla released after the closing bell on Wednesday.

Both Elon Musk's Tesla (TSLA) and Alphabet (GOOGL) released second-quarter earnings after the close on Wednesday, and traders are treating them much the same. Alphabet stock has lost 1.6% at the time of writing, while TSLA has given up 1.0%.

Tesla has normally been a good investment. While it hasn't always outperformed the market, the automotive stock has generated returns of around 1,700% over the past decade, while the S&P is up around 200% over that time frame. Tesla's good years have more than outweighed the bad ones during that stretch.