What company owns Sentinels?

I'm curious to know, which company holds the reins of Sentinels? I understand that Sentinels plays a significant role in the blockchain and cryptocurrency ecosystem, but I'm having trouble pinpointing the specific company that stands behind it. Could you please enlighten me on the identity of the company that owns and operates Sentinels? It would be greatly appreciated if you could provide me with a clear and concise answer.