Smiling from ear-to-ear, the man known as The Cat rang the bell at the Australian Securities Exchange in Sydney at noon on Thursday and officially opened trade in shares of real estate classifieds and services business Domain.

Describing the moment as "the most nerve-racking and exciting day of my life", Domain chief executive Antony Catalano watched as the business he has led since 2013 began its life as a listed entity with a market capitalisation of $2.2 billion.