You make $100,000 Trading. You start a business and for that year it looses $10,000. Can you deduct the $10,000 you loss from the $10,000 from trading?
It has to be set up properly, you need a CPA. The trading income is normally capital gains, unless you are a MTM trader or trading under an LLC. You can capture the business loss as a NOL, and deduct it against ordinary income, and that can be carried forward. DO NOT use the tax advice of this forum.