Although Tesla enjoys a surge in their stock prices, observers warned bullish investors to take precaution on trading decisions.

Jeff Reeves, editor of InvestorPlace.com, earlier surmised that the rise of Tesla Motors' (TSLA) stock will have to end. Citing 300 percent gains in TSLA stock "hardly sustainable," he further said that "Investors need to be prepared for continued volatility after Tesla earnings." Reeves, in his report, initially credited "supply issues at Tesla and competition from entrenched automakers" as factors that would halt Tesla's 52-week high in the stock market. He further cautioned bullish investors to take a bearish approach on Tesla earnings as "the volatility [of Tesla earnings] is going to get severe." To be bearish is to anticipate that stock prices will go downward.

Automotive industry report Mike Ramsey of the Wall Street Journal commented that he isn't comfortable with the way investors "reward[ing] him [Tesla Motors' CEO Elon Musk] by putting a value on the company that defies easy comparisons." This observation was secondhanded by Tesla Motors' shareholder and Motley Fool contributor Tamara Rutter as she identified that the car marker "included both GAAP and non-GAAP figures as a way to show sales" and boost earnings. Non - generally accepted accounting earnings may or may not include cash, operating and pro-forma income, and earnings before income, taxes depreciation. These figures are merely indicators of a company's performance, but does not mean that a company earns cash.

Trading today saw Tesla Motors' (TSLA) shares increase as much as 15% at US$155.85 in trading after hours.