Barclays is saying the cryptocurrency mining-driven demand for AMD's graphics cards will not last and is telling investors to avoid the chipmaker's shares.

The bank's semiconductor analyst, Blayne Curtis, reiterated his underweight rating and his $9 price target for AMD, representing 33 percent downside from Monday's close.



"We are revisiting AMD's last earnings release with an analysis of the [Ethereum] tailwind, which now appears to be the source of the better revenue in June/Sept [guidance], and why investors should place very little value on this earnings stream," Curtis wrote in a note to clients Tuesday. "We believe estimates could be too high next year should this [Ethereum] tailwind dry up."



Cryptocurrency miners use graphics cards from AMD and Nvidia to "mine" new coins, which can then be sold or held for future appreciation. AMD traditionally has a better reputation for mining cryptocurrencies such as Ethereum, according to Wall Street.



Ethereum cryptocurrency is up more than 3,300 percent year to date through Tuesday, according to data from industry website CoinDesk.



The analyst said that outside the cryptocurrency mining market demand, AMD has lost market share to Nvidia in the gaming market, according to data from Steam, a digital PC game store. In addition, he estimates due to high graphics card prices in the secondary market it is now not profitable to mine Ethereum.

"We still believe AMD is seeing little traction with its server chip (Epyc) and this likely crypto headwind only bolsters our underweight thesis," Curtis wrote.



The company's shares are one of the market's best-performing equities in the past year with the stock up nearly 100 percent in the past 12 months through midday Tuesday compared with the S&P 500's 14 percent return. That performance ranks No. 3 in the entire S&P 500, according to FactSet.

The chipmaker reported better-than-expected second-quarter earnings and guidance last month.



AMD sent the following statement in response to this story:

"While our GPUs have obvious applications in cryptocurrency, our main corporate focus remains on PCs, Gaming, and the Datacenter. We realize the uncertainty of the cryptocurrency market and are not looking at it as a long-term growth driver, but we'll certainly continue to monitor the developments around blockchain technologies as they go forward."

— CNBC's Michael Bloom contributed to this story.