The short answer is the Dutch East India Company, chartered in 1602. It was enormous because of its monopoly of the spice trade and, per Ricklefs (1993, 2nd ed), paid an annual dividend of around 18% for nearly 200 years.

Mate, I'm going to ask you to rephrase and resubmit this question. "Big" is such a relative term that you've asked a question that's going to be impossible to answer in a quality way, and you're going to get a bunch of short, poorly cited answers.