The U.S. stock market just enjoyed its best month since 2020, but that also means some weak stocks received unwarranted support and could soon fall back, according to Barclays. The British bank put together a list of stocks that its analysts rate underweight and that have large downside risk with little potential upside. "We define negative risk/reward as the absolute ratio between the stock's downside to its downside case and its upside to its upside case, looking for a ratio of at least 2:1. We applied this factor to our universe of 120+ Underweight-rated stocks in North America," Barclays said in a note to clients. The stocks below are trading at least 10% above their Barclays price targets. Source: Barclays The name on the list with the most downside, according to Barclays analysts, is health-care stock Illumina . Shares of Illumina rose more than 17% in July, and closed the month at a price of $216.68. That gives Illumina downside of more than 30% to Barclays' price target of $150. Another stronger performer on the list is Liberty Media Formula One . The sports stock rose more than 6% in July and is now up 7.2% year to date. Barclays' bearish outlook on Formula One is not shared by many on Wall Street. The stock still has a buy rating from more than half of the analysts covering the company, according to FactSet. The investment firm has a price target of $50 per share for Formula One, which is more than 26% below where the stock closed Friday. One stock on the list that underperformed last month was Domino's Pizza . However, the chain still finished up July a little higher, despite missing earnings estimates for its second quarter . Domino's said same-store sales declined while analysts had been expecting 5% growth, according to StreetAccount estimates. Barclays has a price target of $350 per share for Domino's, implying downside of nearly 11% for the stock. — CNBC's Michael Bloom contributed to this report.