Hello and thank you for your question.
Losses are deductible under IRC 165 here:
As an individual taxpayer, I assume you had an investment in GM. If you are out your investment, you'll qualify. Under IRC 165(c), individual taxpayers are entitled to take losses in accordance with IRC 165(a) in the following situations:
(c) Limitation on losses of individuals
In the case of an individual, the deduction under subsection (a) shall be limited to—
losses incurred in a trade or business;
losses incurred in any transaction entered into for profit, though not connected with a trade or business; and
except as provided in subsection (h), losses of property not connected with a trade or business or a transaction entered into for profit, if such losses arise from fire, storm, shipwreck, or other casualty, or from theft.