OpenAI, the maker of the hit chatbot ChatGPT, made official its prep for a blockbuster public listing – where it will test investor appetite for its cash-burning business. The Sam Altman-led company – which ignited the artificial-intelligence frenzy in 2022 – said Monday that it confidentially filed initial public offering paperwork with the Securities and Exchange Commission, setting OpenAI up to go public as soon as the fall.  An OpenAI IPO – along with planned listings by its competitors