Shares of American Express Co. /zigman2/quotes/203805826/composite AXP +0.65% sank 2.1% in morning trading Wednesday, after BofA Securities analyst Mihir Bhatia turned bearish on the credit card and travel services company, citing concerns over billing volumes, particularly in airline and lodging. Bhatia lowered the rating on the stock to underperform, or the equivalent of sell, from neutral, and trimmed the price target to $95 from $106. "BofA Sector Analysts estimate it could be 2024 before spending volumes on airlines and lodging are at 2019 levels, and a full recovery is dependent on a vaccine being available and widely administered," Bhatia wrote in a note to clients. "We believe spending volume or billings is perhaps the most important metric for [American Express]," Bhatia added. The stock has dropped 22.5% year to date, while the Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA +0.40% has slipped 4.2%.