There really isn't anything like HN for the alternative investments industry.
The business, finance and economics news found in major newspapers like WSJ and FT catch a lot of the relevant news stories.
The nature of the work and how the industry operates are such that there won't be public discussions like you find in the "Show:HN" or "Ask:HN" sections.
As another comment mentioned, the bloomberg terminal has news. And it also has a chat feature, so a lot of discussions happens on there.
Obviously BB terminals are crazy expensive, so it's hard for people not working in the industry to access that info, but if you live in NY the NY library has a few terminals that anyone can use.