Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Tesla Motors (Nasdaq: TSLA) were the victim of a high-speed head-on collision today, with shares suddenly crashing midday by 20% on massive volume after Bloomberg reported the departure of two key executives.

So what: Two employees involved in the development of Tesla's Model S electric luxury sedan have left the company. Peter Rawlinson, chief engineer, and Nick Sampson, involved in vehicle and chassis engineering, have called it quits, even as the Model S is set for a debut later this year. The news naturally sparks fears that something terrible is laying in the weeds for the Model S, which Tesla now has everything riding on as it's been winding down production of its pricey Roadster to make way for the Model S.

Now what: Tesla is also set to unveil its Model X electric SUV early next month as it focuses on more affordable mainstream offerings. Company spokesman Ricardo Reyes said that Rawlinson had finished conceptual and design engineering work on the Model S and was leaving to tend to personal matters in the U.K., while Sampson had transitioned off the Model S by the time he left without offering any more detail. Tesla has filled Rawlinson's spot with a former engineer with Daimler, Jerome Guillen, and also hired a former Volkswagen exec, Eric Bach.

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