Investors who have been stunned by Tesla's stock-price surge need to keep a key vulnerability in mind (TSLA)

· Tesla's stock has enjoyed a stunning rise in the past three months.
· The company is now comically overvalued, with a market cap that's well over $100 billion.
· Investors have discounted Tesla's total exposure to the still-tiny electric vehicle market and have also argued that the carmaker deserves a tech-company...