New York Attorney General Eric Schneiderman is investigating why Exxon Mobil Corp. hasn’t written down… New York Attorney General Eric Schneiderman is investigating why the oil giant hasn’t written down the value of its assets even as others have done so due to plummeting crude prices. It is an issue that is particularly knotty in the energy industry, where the rules about valuing and writing down assets are complex. And a lot depends on what a company expects for the future: Will oil prices rebound, or stay mired below $50 a barrel? The answer can make a big difference for investors — if a company decides its assets have lost value and should be written down, it hurts earnings and book value, or a company’s net worth. And the leeway allowed in making that decision means there is always a motivation for a company to be overly optimistic about […]