Investors clearly expected great things from Tesla Motors’ third quarter earnings report, released Tuesday.

The upstart automaker beat Wall Street’s expectations, posting a pro-forma profit of $15.9 million - or 12 cents per share - on strong sales of its electric Model S sedan. Tesla also reported rising production at its factory in Fremont, churning out 550 cars per week.

But some analysts and investors had been hoping for more. The company’s high-flying stock plunged 11 percent in after-hours trading, dropping to $157 per share.

It was a typically odd turn of events for Tesla, whose success with the Model S has turned its stock into one of the market’s most hotly debated.

By many metrics, the company had a solid quarter.

Palo Alto’s Tesla delivered 5,500 cars during the quarter, including 1,000 to Europe. Deliveries have increased steadily since the Model S first hit the market, in June 2012. Tesla now expects to ship 6,000 cars in the fourth quarter, reaching 21,500 for the year. The Model S ranges in price from $69,900 to $94,900, before state and federal incentives are factored in.

The company’s $15.9 million pro-forma net income, which excludes the accounting effects of Tesla’s auto-leasing program, marked the company’s third consecutive quarterly profit. It also represented a sharp turnaround from Tesla’s $97.1 million loss (or 92 cents per share) during the third quarter of 2012.

Under generally accepted accounting principles, the company lost $38.5 million during the quarter, down from $110.8 million during the same period last year.

Revenues reached $431.3 million, up from $405.1 million in the second quarter and $50.1 million during the third quarter of 2012.

Investors may have been hoping for a blowout quarter, particularly in the automaker’s production and delivery numbers. Recent speculation on investment websites had suggested that Tesla might have shipped as many as 7,000 cars, far higher than the 5,150 delivered during the second quarter.

Tesla’s stock has been sliding in recent weeks, following two vehicle fires that received widespread attention on the Internet, even though neither appeared to have been caused by a flaw in the Model S design. Chief Executive Officer Elon Musk also helped deflate the stock price after he was quoted in the Financial Times saying the company’s valuation was higher than Tesla had “any right to deserve.”

Investors are waiting to see whether the initial strong demand for the Model S will grow as the company expands into Europe and Asia. Tesla reported Tuesday that it will begin delivering the Model S to China in the first quarter of next year.

“There’s absolutely been a novelty factor,” said Karl Brauer, a senior analyst with the Kelley Blue Book auto information service. “The question is always how big and how sustainable is that market? We’re still in the niche phase.”