Super Micro Computer, whose auditor unexpectedly stepped down last week, flagged uncertainty Tuesday about the timing of its annual report but said a probe about accounting practices had not found evidence of fraud by the company.

Shares of the San Jose, California-based server maker fell about 15.5% to $23.42 in extended trading.

The company also said it expects net sales of $5.5 billion to $6.1 billion for the second quarter, compared with analysts' estimates of $6.86 billion, according to data compiled by LSEG.

Super Micro expects profits between 48 cents and 58 cents per share, far below estimates of 75 cents per share.

Super Micro has also become a key supplier to specialty cloud-computing providers such as CoreWeave that focus on providing chips from Nvidia for artificial-intelligence work.

On a conference call with investors, Super Micro Chief Executive Charles Liang said the company's forecast reflected the fact it is waiting for Nvidia's latest chips. Liang said the computer servers Super Micro will build around those chips are ready for production and that it does not expect any reduction in its allocation of Nvidia chips.

Liang, who founded Super Micro in 1993, the same year Nvidia was founded, also said he has an open mind about separating the company's chairman and chief executive roles, both of which he holds.

Super Micro's preliminary results come less than a week after Ernst & Young resigned as its auditor, triggering investor concerns about accounting practices at the firm.

The special committee probe related to issues raised by EY over the company's governance, transparency and internal control over financial reporting.

Super Micro risks being delisted from the Nasdaq if it does not meet deadlines later this month. The recent departure of EY adds a layer of complexity to this compliance restoration process.

On the conference call, Super Micro executives declined to answer questions from analysts about when the company would file its annual report or secure a new auditor.

"It feels like yesterday this was a stock-market darling, showing how quickly things can change for investors and companies alike," said Ryan Detrick, chief market strategist at investment advisory firm Carson Group.