If your investments end up losing money, rather than generating capital gains, you can use those losses to reduce your taxes. The IRS allows you to match up your gains and losses for any given year to determine your "net" capital gain or loss. If you end up with a net loss, you can use up to $3,000 per year to reduce your taxable income. Any additional losses can be carried-forward into future years, to offset either capital gains or another $3,000 in ordinary income.
Enter your 1099-B information and the program will calculate any gains or losses and offset them as appropriate.
Please read the TurboTax FAQ for more information about: "Where do I enter a capital gain or loss?":
Where do I enter a capital
gain or loss?
Please read the TurboTax FAQ for more information about: "What is a capital loss carryover?":
What is a capital loss
carryover?
Capital Gains & Losses: https://turbotax.intuit.com/tax-tips/investments-and-taxes/capital-gains-and-losses/L7GF1ouP8