What happened

Shares of electric-truck start-up Nikola (NASDAQ:NKLA) were trading lower for a second day on Friday morning, after a Deutsche Bank analyst talked up the company's future prospects -- but didn't recommend that investors buy its shares.

As of noon EDT, Nikola's stock was down about 3.5% from Thursday's closing price. 

So what

Deutsche Bank analyst Emmanuel Rosner initiated coverage of Nikola in a note on Thursday with a hold rating and a price target of $54, slightly below the stock's closing price ($54.58) on Wednesday. 

Rosner is hardly a Nikola bear, though. He thinks the stock gives investors "a rare pure way to invest in zero-emission commercial trucks," a sector that is likely to grow strongly in coming years, and that Nikola could well sell over 15,000 trucks a year by 2025, generating revenue of $4.6 billion per year.

A red Nikola Two semi hauling an Anheuser-Busch trailer.

Nikola is hoping to begin shipping its electric semis by the end of 2021. Image source: Nikola Corporation.

But, he said, there's some reason for caution. While Nikola's stock is trading at an enterprise value to sales multiple that is similar to those of Tesla (NASDAQ:TSLA) and NIO (NYSE:NIO), Nikola -- unlike both NIO and Tesla -- hasn't yet produced any trucks. It won't even have its factory up and running for at least another year. 

Right now, Nikola doesn't have any revenue at all, and that makes it a risky bet. 

Now what

It's hard to argue with Rosner's takeaway. While Nikola's story is a good one, it has yet to show that it can execute. At the moment, it's fully priced for its likely best-case scenario five years from now, despite the considerable risk of things going awry between now and 2025. Auto investors should exercise some caution here.