The NYSE has very stringent requirements that make it tough for smaller companies to be listed on it. This is why we usually see the biggest companies on there.
NASDAQ is more friendly for start-ups and tech IPOs (Initial Public Offering). They still have lots of requirements but not as tough as NYSE.
A lot of companies start their public life in the OTC (Over the Counter) markets, then switch to NASDAQ or NYSE depending on their current financial strength. With the bigger IPOs, a company will start off on the NASDAQ and then switch to NYSE.
Why would they do this? Historically, the NYSE is the most trusted exchange for traders, which gives it a lot more volume.
