[aidscholar]

Sounds like overaggressive spam detection.

[joepawl]

This sounds like the case. Google is getting aggressive with its Panda updates, and as a previous commenter noted, the HN homepage is just links. Since that triggers Panda, it's a good bet that Google went a little overboard (not unprecedented).

[mahranch]

> the HN homepage is just links. Since that triggers Panda

To be more specific, Panda is triggered by low quality/duplicate content. 'Penguin' is triggered by spammy/bad backlinks.

I'm not saying you're wrong (a page of links would look pretty low quality to google's algo), I just wanted to add on for clarity's sake.

[joepawl]

Yes, I see where I was unclear. It's not the links themselves, but the lack of original, robust content.

[Roedou]

The Panda update definitely pushed lazy/low-quality pages down the SERPs, but doesn't tend to deindex pages.

Also: while the page doesn't have any of its own unique content, it presumably still has high engagement and low bounce rate.

[joepawl]

That's a good point. Hadn't thought the issue through that far.