Elon Musk. Alain Jocard/Getty Images Elon Musk's X app is looking to build a stock-trading hub within the platform, according to Semafor. The outlet cited sources and a request for plans sent to large financial-data firms by X. Musk said, "No work is being done on this to the best of my knowledge." Elon Musk's X app, previously known as Twitter, is seeking help in becoming a stock-trading hub for its users, Semafor reported. Citing sources familiar with the matter and a request for plans, Semafor said the social media company has reached out to financial-data firms in the past…