Tesla shares may be up 400% this year, but one investment researcher is sounding the alarm on the stock. New Constructs CEO David Trainer calls Tesla the most dangerous stock on Wall Street and says the fundamentals do not support such a high price and valuation. "Whatever best-case scenario you want to paint for what Tesla's going to do – whether they're going to produce 30 million cars within the next 10 years, and get in the insurance business and have the same high margins as Toyota, the most efficient car company with scale of all-time – even if you do believe all that is true, the stock price is still implying that profits are going to be even bigger than that," Trainer told CNBC's " Trading Nation " on Thursday. He notes that the stock price is implying anywhere from a 40% to 110% market share based upon the average selling price. At its current average selling price of $57,000 and assuming 10.9 million car sales by 2030, that implies 42% market share, Trainer says.