Jack Dorsey is best known for launching Twitter, now firmly under control of its new CEO Elon Musk.

But he has other companies too, including fintech company Block, once known as Square.

Hindenburg Research has announced that Block was its latest short position, having accused the company of widespread fraud in performance metrics.

On Thursday, Hindenburg released a report claiming that Block misleads investors by overstating numbers with “fake and duplicate accounts.” Included in the report were a number of financial crimes and (at best) unethical practices. They say the company has “systematically taken advantage of the demographics it claims to be helping.”

The report says Block targeted minorities, millennials and Gen Z with inflated fees and loan rates. It reads in part, “The ‘magic’ behind Block’s business has not been disruptive innovation, but rather the company’s willingness to facilitate fraud against consumers and the government, avoid regulation, dress up predatory loans and fees as revolutionary technology, and mislead investors with inflated metrics.”

Block responded in a statement with a scathing denial, calling the report “factually inaccurate and misleading,” and threatening legal action. The statement read in part, “We are a highly regulated public company with regular disclosures, and are confident in our products, reporting, compliance programs, and controls. We will not be distracted by typical short seller tactics.”