The origin of the NYSE can be traced to May 17, 1792, when the Buttonwood
Agreement was signed by 24 stock brokers outside of 68 Wall Street in New
York under a sycamore (or Buttonwood) tree on Wall Street which earlier was
the site of a stockade fence.The organization drafted its constitution on March
8, 1817, and named itself the "New York Stock & Exchange Board". In 1863,
this name was shortened to its modern form, "New York Stock Exchange".

Depiction of stock brokers under the sycamore tree.