Jack Dorsey (L), CEO of Square and CEO of Twitter, is congratulated by Jim McKelvey, co-founder of Square, (2nd R) and NYSE President Tom Farley (R) after the IPO of Square Inc., in New York

Jack Dorsey (L), CEO of Square and CEO of Twitter, and Jim McKelvey, co-founder of Square, (2nd R) applaud as NYSE President Tom Farley (R) fist bumps Mac Riley after the IPO of Square Inc., in New York

Jack Dorsey (L), CEO of Square and CEO of Twitter, and Jim McKelvey, co-founder of Square, speak during an event outside of the New York Stock Exchange to celebrate the IPO of Square Inc., in New York

Jack Dorsey (L), CEO of Square and CEO of Twitter, live casts video of his mother (C) as she hugs a vendor after using her Apple watch to make a purchase with a Square reader outside the New York Stock Exchange for the IPO of Square Inc., in New York