Short seller Hindenburg Research claimed on Jan. 2 that its research team uncovered $800 million in credit sales by used car retailer Carvana Co to a suspected unnamed related party, Reuters reported.

“Our research uncovered $800 million in loan sales to a suspected unnamed related party, along with details of how accounting manipulations and lax underwriting caused a temporary increase in reported revenue,” Reuters quoted Hinderburg’s allegations in its report .

After the report was released, shares of the Tempe, Arizona-based company fell as much as 5 percent but pared losses to trade up 1.5 percent.

What Hindenburg Research said in its report:

Hindenburg claimed that her research included an extensive document review and 49 interviews with industry experts, former Carvana employees, competitors and the company’s related parties, conducted over a four-month period, and showed that Carvana’s turnaround is a mirage.

Hindenburg explained that Carvana’s business is already facing major headwinds. Citing the Manheim Price Index, Hindenburg claimed that used car prices have fallen 20.3% over the past three years.

Additionally, the short seller claimed that Carvana has been telling investors for at least six years that it is seeking to diversify outside of its relationship with Ally, but has not yet announced any new financing partners.