MicroStrategy Inc. can’t strip out Bitcoin’s wild swings from the unofficial accounting measures it touts to investors, the SEC said.

Bad news for the MicroStrategy was compounded as the company’s shares fell as much as 20% Friday, the biggest intraday collapse since Feb. 23. Its stock closed at $375.89, down nearly 18%. Bitcoin also tumbled, and was down more than 7% around 4:15 p.m. in New York.

U.S. generally accepted accounting principles, or GAAP, offer no rules for reporting the value of digital assets. Nonbinding guidance from the American Institute of CPAs says companies should classify the currency as an intangible asset, as outlined in ASC 350. This means businesses that don’t qualify as investment firms would record cryptocurrency at historical cost and then only adjust it if the value declines. Once their holdings get written down, or impaired, companies can’t revise the value back up if the price recovers.