The Mississippi Company was never really worth $6.5T in any meaningful sense. Unlike Dutch East India, Mississippi was purely a speculative bubble. It only hit that value for a few weeks at the end before the whole thing imploded.
That said, you could make a similar case about apple. If you measure by dividends, I think the VOC's lead over all those companies grows by a lot.
What alternatives exist for defining value?
What do we mean by value?