Shares of Super Micro Computer (NASDAQ:) fell about 6% in New York trading on Tuesday after a critical report from short seller Hindenburg Research was released.

The research firm highlighted several concerns about the company’s accounting practices and corporate governance that could raise alarm among investors and shareholders.

SMCI, a server maker valued at $35 billion, has been under scrutiny for failing to file financial reports since it was delisted from Nasdaq in 2018. Despite a $17.5 million settlement with the SEC in August 2020 over accounting violations, Hindenburg said the company resumed questionable practices shortly thereafter.

The allegations include improper recording of sales and the rehiring of executives who were involved in previous accounting scandals.

“Less than three months after paying a $17.5 million settlement to the SEC, Super Micro began rehiring top executives who were directly involved in the accounting scandal, according to trial documents and interviews with former employees,” the brief said.

Other issues highlighted by Hindenburg Research concern Super Micro’s relationships with affiliated companies.

The brothers of Super Micro CEO Charles Liang reportedly control suppliers Ablecom and Compuware, which received $983 million over three years. These relationships, described as circular, involve transactions that are not fully disclosed and pose risks to revenue recognition and reported margins, Hindenburg said.

Super Micro’s integrity has also been questioned in its dealings with sanctioned countries. Despite an admission of guilt for exporting banned components to Iran in 2006 and pledges to comply with US export bans on Russia following the invasion of Ukraine, the report suggests that exports to Russia have increased, potentially violating sanctions.

The report also cites competition and quality issues leading to the loss of key customers. Major companies such as Nvidia (NASDAQ:), CoreWeave and Tesla (NASDAQ:) have reduced their dependence on Super Micro and opted for competitors such as Dell (NYSE:).

Customer service and product reliability issues have further damaged the company’s reputation, with some customers reporting high levels of disruption and service issues.