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Is it legal if I'm managing my family's entire wealth?
You are opening up a large can of worms with how you are doing this.  In very positive years, you'll have taxes based on your income, potential Alternative Minimum Tax (AMT), etc. Each of the family members may be in a lower bracket, perhaps even needing to pay zero on capital gains.  Even if you are 100% honest, if you are subject to a lawsuit, these funds are all in your name, and you'd be in a tough situation explaining to a court that these assets aren't "really" yours, but belong to family.  And last, the movement of large chunks of money needs to be accounted for, and can easily run afoul of gifting rules.  As mhoran stated, a Power of Attorney (POA) avoids this. When my father-in-law passed, I took over my mother-in-law's finances, via POA. I sign in to my brokerage account, and her accounts are there. I can trade, deal with her Individual Retirement Account (IRA) Required Minimum Distributions (RMDs) each year, and issue checks to her long term care facility. It's all under her social security number - our money isn't intermingled.