I have written a series of articles on ethanol producer Pacific Ethanol (PEIX) since Q3 2018 that have focused on the shortcomings of book value as a valuation measure for heavily-indebted companies that are caught in a structural oversupply environment. The company's share price has declined by as much as 92% over that time as ethanol production margins have moved steadily downward amid continued overproduction by U.S. ethanol producers (see figure).
An interesting observation that has been made frequently in the comments of these articles has noted that Pacific Ethanol's