There are very few bright lines in state residency for tax purposes and it's generally a "have to pay the worst possible amount unless proven otherwise" situation. Also confused by the fact that the people asking these types of questions always seem to leave out some crucial facts to make it seem more to their liking. With that in mind:
1. Which 4 months are you spending in CA? If it's the last 4 months of the year, that would tend to indicate you're moving there. If it's the first 4 months, it would tend to indicate you moved away.
2. When did you generate the income and what kind is it? If you work a W-2 job your employer is required to do withholdings and UI in CA, so they know it was generated there and when. You'll owe CA taxes on that absent a couple edge cases (spouse of a military member with residency in another state, for example).
3. When you earned the stock income is a little greyer. If you earned it while living in CA (remember from above they may know exactly when you lived there) then they're going to claim it for tax purposes. Even if you didn't, if it's a futures contract they could ask you to MTM at the time you left. Probably unlikely they would initiate this out of the blue, but if you get audited for something else.....
4. Did you actually move to the other state? Renting a room on the Nevada side of South Lake Tahoe and registering your car in NV may or may not cut it. If you really have no other ties to CA, you're probably good. Forgot to tell us your wife still owns your house in LA? Completely different story.
And of course that all ignores the fact that you have to first make $100K off futures trading, at which point you'll be able to easily afford professional advice for this