Workspace-sharing company WeWork warned Tuesday of a “substantial doubt” about its ability to continue operating over the next year, citing financial losses and the need for more capital among factors threatening the business. The New York-based company, which was once valued at $47 billion, has suffered a series of setbacks in recent years, including a botched attempt to go public in 2019 and the departure of co-founder Adam Neumann. The company’s shares fell by almost 24 percent in extended trading in New York in the wake of the announcement, adding to WeWork’s woes after the COVID pandemic drove workers away from offices and dramatically increased difficulties in the commercial real estate market.