Optimism about AI-related growth has helped shares of Microsoft (MSFT) this year, but at least one investment bank is urging caution about what mig🐷ht come next.

Oppenheimer analysts on Tuesday downgraded shares of Microsoft to “perform” from “outperform.” That's rare on Wall Street, with nearly all of the analysts currently tracking the software giant holding "buy" or equivalent ratings, according to Visible Alpha.

Shares of🍎 Microsoft were recently up about 1%, slightly outperforming the broader market. The stock is up more than 11% for the year.

"Open AI losses are the primary concern and could be in the $2-3B range in FY25, which we were not previously modeling," the analysts wrote Tuesday. Open AI is an independent company, but it has a "strategic partnership" with Microsoft. “Entꦿerprises have been slow to adopt AI and associated revenues will likely disappoint.”ꦡ

In a September report, Oppenheimer said it was “tweaking down near term AI revenue, but tweaking up CapEx spending, mostly for Microsoft.” The company is investing in "once-in-a-generation technology," the analysts wrote, so "we don’t believe expanding margins will be a short-term priority.” 

Oppenheimer also said that Microsoft's shares are trading near the midpoint of the five-year range for its price-to-earnings ratio and "could trade to the lower end" down the line.