There are a great many activities Grand Theft Auto 5 players can get up to including tennis, property buying, maybe some actual crimes, and taking a gamble on the game's stock market.
Over on Reddit, users have complied a list of the game's companies and their competitors suggesting the best course of action is to rob one firm and invest in its rival.
The list of the game's main companies and their competitors is below.
For example, at one point you're given a mission to kill a cigarette company's boss. Now would be the optimal time to invest in the other cigarette company is Los Santos. Lester mentions that people who invested in the rival cigarrete company to Redwood Cigarettes – Debonaire – get a lot of money after successfully completing that mission.
Grand Theft Auto 5 predicatbly made a mint in the real world as well bringing in a staggering $800 million in revenue in its first 24 hours. The game has also became the fastest launch in the UK ever.
You can find some of the game's cheats here.