Who was the first company to advertise his own product?

As advertising may be loosely defined as using tools of communication to promote an idea, product, or service, the first person to utter his own name would qualify as the first marketer. In business, any paid communication intended to bring in new potential revenue could be considered advertising. One of the oldest organized groups with official rules of conduct (a "company") were Assyrian merchant groups thousands of years ago.

The ancient Assyrian merchants were a higher social class than the artisans, farmers and priests, and would use influence to attract more business. The merchants directly and indirectly reported to scribes that would record and report merchants' progress. Scribes also held much influence with the king.

It can be argued that there were many other companies preceding the Assyrian merchant groups of 1750 BC (approx. date of the oldest known documents addressing private trade), and I'm confident that all of them also traded goods or services in exchange for greater market share.