JPMorgan is advising investors to bet against shares of electric-car maker Tesla because the company is likely to raise more capital, diluting its stock.

Also, competition from other automakers will increase, with some established auto giants looking to reap benefits from government subsidies, wrote analyst Ryan Brinkman.

"Tesla will face several milestones in 2018 relative to the ramping of production of the Model 3, which we believe will be difficult for the company to meet, particularly if its substantial miss to volume targets in 2017 are to be any guide," wrote Brinkman on Friday.

"Competition for electric vehicles will increase in 2018 even as the regulatory environment in the United States may become less of a tailwind, including possible tax law changes and exhaustion of the $7,500 US federal tax credit available to buyers," he wrote.

This isn't the first time Wall Street has advised investors to short Tesla. Famed short seller Jim Chanos of Kynikos Associates said last month that he had increased his short position throughout the year, telling Reuters that he expects CEO Elon Musk to walk away from the company by 2020.

By selling shares at their current price and covering the sale at a later date, investors hope to profit as the price of Tesla shares fall.

Much of the short selling stems from doubts that Tesla will be able to bring its mid-priced Model 3 to full production, having delivered far fewer sedans than expected in 2017. Though many would consider Tesla integral in pushing the auto industry toward an electric and autonomous future, concerns of competition are creeping into the conversation.

"One of our principal concerns relates to how Tesla is going to be able to earn even an industry average EBIT margin if it must compete against competitors that are pricing electric vehicles without even the intention to make money, but rather to subsidize the rest of their lucrative internal combustion engine portfolios from a legal and regulatory compliance perspective," added Brinkman. The analyst has an underweight rating on Tesla as well as a $185 price target, representing 40 percent downside from Thursday's close.

To be sure, Tesla shorts have not had success for the majority of 2017, down roughly $4.1 billion for the first three quarters of the year on an average short position of $9.4 billion, according to an S3 Partners note published last month. Shares of Tesla are up 45 percent since January but were down 0.8 percent Friday.

However, from a high of $385 per share in September, Tesla's stock has lost one-fifth of its value, with shorts recovering $890 million of their losses, according to S3 Partners.

Alternatively, Brinkman is long on shares of Tesla rival General Motors, which he sees rising 28 percent over the next year.

"We note General Motors sports a 3.4 percent dividend yield, making it attractive to income oriented investors, and yields 8.9 percent free cash flow to equity, on our 2018 estimates," wrote Brinkman. "Investors have not been willing to accord GM shares the premium we feel they deserve, given: (1) fear of large losses in the next downturn; and (2) fear of disintermediation by Silicon Valley."

General Motors shares are up 24 percent since January but fell 1.1 percent Friday.