I'm not familiar with the messagebird story but there have been other later stage companies in YC before. For example, Quora entered YC when worth $900 million. https://techcrunch.com/2014/05/11/quora-y-combinator/
>There are a bunch of reasons why it's valuable for Quora to be a YC company:
>We'll have Sam and all the other partners to help us.
>We get to be part of the YC community / alumni network of founders.
>We get access to all the resources of YC.
>We were raising money anyway, so there was no overhead in letting YC participate - this ends up the same for us as if we had just raised slightly more money from Tiger. And independent of the benefits to Quora, I think it will be fun personally to participate in some of the YC events. I hope my perspective can help some of the other companies.
