This should worry the Tesla shorts

As if a 70percent year-to-date rally weren't enough, Tesla CEO Elon Musk has given the world another thing to be excited about.

In a tweet early last week, Musk wrote:

About time to unveil the D and something else

— Elon Musk (@elonmusk)

That, of course, had people wondering what the devil the "D" is and what is that "something else," too. The company is scheduled to make a big announcement on Thursday, Oct. 9 but speculation is Tesla will unveil an all-wheel drive vehicle. Three weeks ago, Musk created a buzz when he said they were working on a self-driving car to be released within the next three years.

(Watch: Bet on Tesla ahead of unveil? Pros disagree)

While there may be excitement for new Tesla models, not everyone is excited about the stock.

"We have to continue to take a wait-and-see mode," said Gina Sanchez, founder of Chantico Global.

But Tesla still needs to make sales, said Sanchez, a CNBC contributor. The company is targeting 100,000 vehicles shipped in 2015.

Yet the company has challenges, according to Sanchez. "For all the hype, Tesla is still a small carmaker in a small niche market," she said. "They sell a very, very expensive-but-beautiful car. But if you look at where the big car sales are happening in all electric cars and it's like the Nissan Leaf."

Last month, Nissan sold 2,881 Leaf cars compared withTesla's 1,650 Model S vehicles, according to Motor Intelligence. The Leaf sells for about $29,000, roughly $40,000 cheaper than the Model S.

But it's Tesla's stock price that is getting all the attention from investors. Shares in the company are up over 520 percent in the last 18 months alone.

But it hasn't been smooth driving for the electric car maker. Richard Ross, global technical strategist for Auerbach Grayson, believes that will continue.

"We're seeing more of the same, which is heightened volatility in the name," said Ross, a "Talking Numbers" contributor. "With concept stocks like this – highflying momentum names – anything goes here."

And for Ross, one place the stock could go is down. He sees a potential "head-and-shoulders" pattern forming over the last three months, with a neckline just below $250 per share. "It's not really a headandshoulders until we break decisively beneath that neckline which we've been able to hold," Ross said.

However, the stock has fallen below what Ross sees as an upward-sloping trend line that began in late 2013. He said its next target is the stock's 200-day moving average at around $217.

"That's well below current levels," Ross said. "If you can't stomach that kind of a drop, which we saw just earlier this year, then maybe you shouldn't be in this stock."

(Watch: Who will change the world in the next 25 years?)

On the other hand, Ross also warns short-sellers that things can turn against them as well. "If you want to be a short-seller here, you have to keep that position very small and your stock very tight because we have a 27 percent short interest here," he said. "We also have a CEO that likes to make incendiary announcements whereby you can light this candle at any point to the upside. You can see $300 just in the same breath."

To see the full discussion on Tesla, with Sanchez on the fundamentals and Ross on the technicals, watch the above video.

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