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These are the stocks you should invest into to get max profit from them. You should invest everything(to do this quickly hold down A on Xbox, X on PS3) You should gain a lot of profit from this
Direct answer to question: Yes, invest 100% into it. Just for back fire reasons make saves before each investment just incase something backfires.
Following on from some advice about getting all characters to buy shares in a specific company before completing an assassination mission, how do I actually quit a mission? There's only two ways I can see how:
Save just before starting a mission, and then load once it's started. The downside here is I need to remember to save before every mission in case one turns out to be important for the stock market.
Somehow fail the mission, preferably without committing suicide, where I'm then given the option to Exit.
Unforunately those are the only two methods.
However, in regards to you forgetting to save before, if you have autosave enabled, just load the autosave and it should load the game before you started the mission, but after everything else (it saves when you complete missions, buy clothes, mod a car, etc.)
Pause the game and go across to the online section where you find 'Find New Session'
this will also let you automatically allow you to save the game