1% of GDP seems arbitrary. If I were going for a strictly financial metric, I'd look at how the megacorp ranks against countries on a
GDP league table. Apple would seem to rank around #15, with more value than 90% of the countries in the world.
But even with large market value, a corporation wouldn't be a megacorp unless it fit some of
Wikipedia's criteria:
It refers to a corporation (normally fictional) that is a massive conglomerate (usually private), holding monopolistic or near-monopolistic control over multiple markets (thus exhibiting both a horizontal and a vertical monopoly). Megacorps are so powerful that they can ignore the law, possess their own heavily armed (often military-sized) private armies, be the operator of a privatized police force, hold "sovereign" territory, and even act as outright governments.