Jack Dorsey may have left Twitter, but evidently he can’t escape corporate drama. On Thursday, a prominent short seller targeted another company he co-founded, payments firm Block, accusing it of releasing questionable data about the number of its users. The short seller, Hindenburg Research, further claimed that vulnerable Block customers have been hurt by its “predatory loans and fees.” Hindenburg, which stands to make money if Block’s share prices drops, recently accused Indian conglomerate Adani Group of financial impropriety—claims the company denied—causing its stock to fall by half. As of mid-morning Eastern time on Thursday, Block’s stock was down 11 percent. Dorsey did not immediately respond to a request for comment.