Not as you describe.
Theft losses are not deductible unless associated with a federally declared disaster, like a hurricane or wildfire.
Investment losses are deductible against other investment gains, and if you don't have other investment gains, you can deduct $3000 of your loss this year and carry the rest forward to when you might have a gain.
The difference between a theft loss and an investment loss is the involvement of a thief, someone who benefits from a crime, rather than innocent but incompetent mismanagement. If you buy an investment that is mismanaged and loses value, that will usually be allowed as an investment loss. But if you purchased a scam, where there is a clear thief or thieves who benefitted, then the IRS will likely see it as a theft loss that is not deductible. Sometimes it is not clear if a loss was due to theft or bad (but legitimate) business practices. If you claim an investment loss and are audited, these are the kinds of issues an auditor will look at.
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