What company owns Coinbase?

Can you tell me who the parent company or owner of Coinbase is? I'm curious to know if it's a publicly traded company or if there's a particular individual or group that holds a controlling stake in the cryptocurrency exchange. Additionally, I'd like to know if there have been any significant changes in ownership or investments in Coinbase over the years, and if so, how those changes might have impacted the company's operations and growth.