Your sole proprietorships' profits and losses will cancel out, but you first have to account for each business on separate Schedule C forms: https://blog.taxact.com/schedule-c-self-employment-income/

Form 1040 will tell you to what extent (if any) that Schedule C losses can reduce your taxes on income from stocks.

The government has declared landlording and investing to be 'passive' activities that do not belong on Schedule C. Landlording is on Schedule E. Investing on Schedule D (capital gains/losses) and 1040 (dividends). If you wish to make these activities active, you would have to get a real estate license (for landlording) and become a day-trader (for 'active trader' status). It sounds like your activities in 2020 do not qualify, so they are 'passive'.

When it comes to 'active' income, your sole proprietorships' profits and losses will cancel out, but you first have to account for each business on separate Schedule C forms: https://blog.taxact.com/schedule-c-self-employment-income/

Form 1040 will tell you to what extent (if any) that 'active' Schedule C losses can reduce your taxes on 'passive' income.