Who is its auditor? It’s a simple question, which ought to have a simple answer.

Most public companies in OpenAI’s notional market cap weight class are audited by one of the Big Four: Deloitte, EY, KPMG or PwC. At the lower end of large-cap US stocks, names like Grant Thornton or BDO creep in.

OpenAI’s auditor is not disclosed. Now, as a private company, it is under no obligation to release this information — but it’s not trivial. The lack of information has left several people we’ve spoken to on Wall Street a bit confused.