IRS tips:
If your capital losses exceed your capital gains, the excess can be deducted on your tax return and used to reduce other income, such as wages, up to an annual limit of $3,000, or $1,500 if you are married filing separately.
At times in the past, I've been there.

Trump is playing a different, i.e. corporate, game with Net Operating Losses. This is where creative accounting opens up all kinds of possibilities.