"The downgrade is driven by valuation considerations as the stock has traded in a highly volatile manner since its IPO likely due to its limited public float and is now trading at ~31x EV/NTM Sales, implying limited upside potential from a valuation perspective," wrote Bernstein's Alexia Howard.

There are now no analysts on Wall Street who recommend buying Beyond Meat, a rare phenomenon for a company that just went public last month and comes as a result of its monster run outpacing even the must bullish expectations.

Bernstein downgraded shares of Beyond Meat Wednesday on valuation concerns, joining J.P. Morgan as the latest Wall Street firm this week to cool on the red-hot IPO.

Bernstein went to market perform from outperform. However the firm upped its price target to $123 from $107. There are now zero buy ratings on Beyond Meat and eight hold ratings, according to FactSet. No one says sell.

Beyond Meat shares dropped 25% to $126.04 on Tuesday after J.P. Morgan, a lead underwriter of the IPO, downgraded the stock. "This downgrade is purely a valuation call," the J.P. Morgan note said.

Beyond Meat shares were up more than 600% from the $25 IPO price through their intraday high on Monday before the two downgrades this week, with the rally driven by rising expectations of wider acceptance of the alternative meat and more deals with restaurants. The company on Tuesday released a "meatier" version of its burgers. The shares began trading May 2.

"Despite the valuation considerations, we continue to expect significant growth potential in the plant-based meat category and believe that Beyond Meat is well positioned as one of the frontrunners leading the new wave of plant-based meat products," Bernstein added.

The shares were up 8.6% to $136.85 in midmorning trading.

— With reporting by CNBC's Michael Bloom.