What happened Shares of hybrid-truck powertrain maker Hyliion Holdings (NYSE: HYLN) opened sharply lower on Monday, after a Wall Street analyst cut his bank's rating on the stock. As of 10:00 a.m. EDT, Hyliion's shares were down about 13.1% from Friday's closing price. So what In a new note on Monday morning, UBS analyst Steven Fisher cut his bank's rating on Hyliion to sell, from neutral, and reduced its price target for the shares to $5 from $14. Fisher wrote that he no longer expects the company to meet revenue expectations for 2022 through 2024, which had been a key driver of its valuation. The company has taken longer than expected to hit its go-to-market milestones, undermining confidence in the management team's execution. Hyliion's products -- hybrid powertrains that can be fitted to any heavy truck -- was a good one. But with the market moving toward zero-emissions alternatives, the company may have missed its opportunity. Image source: Hyliion Holdings. More broadly, Fisher expects a "careful" customer adoption rate as the company brings its hybrid heavy-truck powertrains to market. He noted that the macro situation — including ongoing global supply chain issues and a labor-market squeeze — will add additional challenges and delays. To sum up, Fisher said that Hyliion's recent valuation reflects "overly optimistic" expectations for its sales ramp. Now what When Hyliion first made its stock market debut last year, I was impressed with the company's astute management team, its asset-light manufacturing model, and its already-established partnerships with key players in the heavy-truck ecosystem. I felt that its hybrid products were well-positioned to earn sales as trucking fleets moved to "green up" their vehicles. Now, the state of play has changed. On the one hand, Hyliion hasn't brought its hybrid powertrains to market as quickly as electric-vehicle investors had expected. On the other, the attention of the trucking industry has turned more toward the fully electric zero-emissions solutions that are expected to come to market over the next couple of years from major truck makers as well as new entrants like Nikola (NASDAQ: NKLA) and Tesla (NASDAQ: TSLA). Simply put, the window of opportunity for Hyliion's hybrid truck drivetrains may now be closing. Until and unless the company revamps its business plan, I can't disagree with Fisher's assessment. 10 stocks we like better than Hyliion Holdings Corp.When our award-winning analyst team has a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Hyliion Holdings Corp. wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of September 17, 2021 John Rosevear has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Tesla. The Motley Fool has a disclosure policy.Source