The author of the quote may have meant biggest leak in Apple's history, which it may well be.

As for biggest leak in history, maybe the shadow brokers leak of all those NSA tools? I'm not sure if anything huge resulted from the Win2k leak but I'm not too informed about it.

1989, "Nu Prometheus League", I believe the Macintosh ROM's source was leaked:

http://www.nytimes.com/1989/11/20/business/us-inquiry-into-t...

I take it this isn't really floating around out there. :(

I don't know, Apple had all the source code to GS/OS leak a few years ago. Now _that's_ serious!

Wasn't that one a partial leak stripped of some interesting bits?

Nothing significant was missing.

For some reason the press relayed the news as "Windows NT and a small portion of Windows 2k source code were leaked". This was false, possibly started my Microsoft itself to downplay the scope of the leak. Virtually everything was there. Some people built it and booted it up.

I did some research [0] and I cannot find anyone claiming that more than ~15% of the Win 2k source code was available.

People are able to build and boot Win NT, not Win 2k.

[0]: https://www.betaarchive.com/forum/viewtopic.php?f=61&t=33250...

There was a third leak, circa 2003, the Windows Research Kernel, which is what you'd get if, say, you had an academic license as part of a university or something.

That one you could very much build and alter.

Windows NT 4.0, yes. But 2000 would surprise me. To my knowledge, at least the product key handling was missing.