A large fourth-quarter miss from Ford is sending a warning signal to analysts at Deutsche Bank. Analyst Emmanuel Rosner downgraded shares of the automaker to a sell from a hold rating in a note Friday to clients, citing the company's high valuation and downside to its "aggressive" 2023 outlook. The guidance and fourth-quarter miss "in our view showcase considerable operational shortfalls and suggest meaningful downside risk to earnings trajectory," he said. According to Rosner, Ford lacks a clear path toward improving its returns and also runs the risk of an acceleration in electric vehicle losses. He trimmed the bank's price target to $11 from $13 a share, representing more than 23% downside from Thursday's close. Shares shed more than 7% before the bell after Ford reported grim fourth-quarter earnings that fell short of both Wall Street's and its own full-year forecast as it grappled with execution and supply chain management problems. Rosner also cast doubt over the company's 2023 guidance, which calls for between $9 billion and $11 billion in adjusted earnings before interest and taxes in part through more than $2.5 billion in cost-cutting initiatives. "While we expect some benefit from lower commodities prices, we struggle to wrap our heads around such a considerable expected reduction in materials costs, and Ford didn't provide any color on tangible restructuring program that would generate such savings so rapidly," he wrote. As of Thursday's close, Ford shares are up more than 23% this year following a 44% slump in 2022. — CNBC's Michael Bloom contributed reporting.