Tesla stock was up a little to start Wednesday as investors digested a bearish take about the company's humanoid robot, Optimus.

Investors are optimistic about the potential for AI-trained robots. There are two sides to every story, however.

Shares of the electric-vehicle maker were up 0.2% at $410.23 in premarket trading, while S&P 500 and Dow Jones Industrial Average futures were both up about 0.3%. For now, investors seem to be waiting for Nvidia earnings, due Wednesday afternoon, before making major decisions about Tesla and other stocks.

Coming into Wednesday trading, Tesla stock was up about 24% over the past 12 months. Gains value the company at about $1.8 trillion, including CEO Elon Musk's vested stock options, and trading for about 206 times estimated 2026 earnings.

AI is responsible for much of that valuation, with investors believing that "physical AI," or AI applications that interact with the world, will lead to a new era of earnings growth for the auto maker. Tesla's first two applications are AI-trained robo-taxis and humanoid robots.

Tesla launched a robo-taxi service in Austin, Texas, in June. Robots aren't here yet, but Tesla is converting its Model S and X line in Fremont, California, to robot manufacturing capacity.

Robots could be a bigger deal than robo-taxis. In 2024, Musk said Optimus is "literally a $25 trillion market cap situation." Not everyone is convinced.

On Tuesday, GLJ Research analyst Gordon Johnson called Optimus a "delusion," putting a 15% to 20% probability that Tesla will ever deliver meaningful robotics revenue. Wall Street bulls are "assigning near-certainty to it. That's not investing. That's speculation," he added.

There are just too many unknowns for him. For starters, current robots aren't built on an assembly line and likely cost hundreds of thousands of dollars. They need to be mass-produced for about $20,000 to reach volumes that would make robots a trillion-dollar-plus global industry.

Taking everything into consideration, he is willing to value Optimus at $50 billion to $80 billion and thinks Tesla's current valuation reflects a valuation closer to $400 billion.

Johnson's take isn't a big surprise for investors. He is a long-term Tesla bear, rating the shares Sell and recommending a short position -- betting on the stock's decline by borrowing shares and selling them. His price target is a Street-low $25.28. The average analyst price target on FactSet is about $427. The difference between those two price targets is about $1.8 trillion.

What Tesla bulls and Johnson can likely agree on is that robots are a big catalyst for the stock, either way, this year. The third generation of Optimus is due to be unveiled by Tesla in the first half of 2026. Impressing investors will be key for shares in the coming months.