$Mara(MARA.US) has been very hot recently with its Bitcoin concept. MSTR has become one of the stocks with the highest trading volume, and other Bitcoin-related concept stocks like COIN and MARA have also gained widespread attention. The stock prices of MSTR and COIN remain at very high levels with significant volatility. As a result, this leading mining stock, which has recently dropped nearly 30%, has become a focus of attention. With a market cap of around $6 billion and a price-to-book ratio of 2x, considering the upcoming adjustment to digital currency accounting standards effective early next year—where Bitcoin can be directly valued at market prices—I visited its official website to check its Bitcoin holdings and cost situation, aiming to calculate how much MARA's net assets could be boosted by the accounting policy change. Unintentionally, I discovered that the company's annual report last year received a qualified opinion from the auditors, who directly pointed out internal control deficiencies that could affect the accuracy of the financial statements. Reading this instantly eroded my trust in the company. Even if the stock price drops further in this cycle, it’s no longer worth my attention. I also hope everyone takes note of this before investing.