Chipmaker agrees to pay a $5.5 million fine.

The U.S. Securities and Exchange Commission has charged Nvidia for not adequately disclosing to investors that cryptomining was a “significant’ reason for its sharp gaming revenue increase in two quarters in fiscal 2018.

Without admitting or denying wrongdoing, the chipmaker agreed to pay $5.5 million to the SEC.

The SEC charged that in the second and third fiscal quarters of 2018, Nvidia reported a 52% and 25% year-over-year increase in sales of its graphics processing units (GPUs) for gaming, respectively.

But it did not disclose in 10-Q quarterly earnings reports that a surge in cryptomining was a “significant” factor in the sales increase – rather than routine business operations.

Since this increase may not be sustainable, “Nvidia’s disclosure failures deprived investors of critical information to evaluate the company’s business in a key market,” said Kristina Littman, chief of the SEC Enforcement Division’s Crypto Assets and Cyber Unit.

However, Nvidia did have a line of chips specifically for cryptomining known as CMP and it did report in its quarterly earnings that cryptomining was a “significant element” of CMP sales. That said, it could not specifically track how much of its gaming GPUs were used for cryptomining.

The SEC said that Nvidia nevertheless had estimates indicating that cryptomining was a “significant factor” in GPU sales for gaming during those two quarters. Also, the agency pointed out that the company did disclose the impact of cryptomining on GPU sales overall in its annual earnings report for fiscal 2018.

In cryptoming, miners receive cryptocurrency rewards for verifying crypto transactions on a distributed ledger. GPUs are popularly used for cryptomining Ethereum and other cryptocurrencies. The SEC said demand for GPUs soared when the price of Ethereum jumped: rising from under $10 on Jan. 1, 2017 to nearly $800 exactly a year later.