How do I buy OpenAI?

Could you please elaborate on the process of acquiring OpenAI? As a potential investor, I'm interested in understanding the steps I need to take to buy into this innovative company. Is OpenAI publicly traded on a stock exchange, or are there alternative methods for investment such as private equity or venture capital funding? Additionally, what factors should I consider when assessing the potential return on my investment in OpenAI? I'm looking forward to your insights and guidance on this matter.