Reading between the lines, this is my guess as to what's going on:

Goldman Sachs built an internal-use-only tool that relied on some GPL code. Aleynikov is going to claim that this made Goldman Sach's code fall under the GPL, and therefore he has a right to redistribute it.

I hope that's not what's going on, because the pointy-haired ones don't need another reason to be afraid of FOSS.

That is not how GPL works. Let's say you have derived work from GPLed source (DW).

if (you publish binary of DW) then {you have to provide sources of DW under GPL}

Simply it does not apply to in-house (non-published) work. You are fine to keep it closed-source.

I believe you are right.

This article is more coherent.

http://www.fiercecomplianceit.com/story/aleynikov-trial-and-...

It seems like he's essentially grasping at straws after the fact to defend himself. But as has been said, that's not how open source works. I don't think this is actually going to make anyone nervous since clearly no one bought his story. You can lie and not be believed about proprietary licenses too.

... I feel sad actually sympathizes with the prosecution here but that's how it goes.

Or maybe Goldman Sachs built a bunch of stuff internally on top of open-source code.

In which case, they could have been in violation if it was GPL code.

Generally, you're only required to provide changes if you are distributing your modified program. This may have been partially addressed in GPLv3 in the form of an "application service provider" clause, but I don't recall

I doubt they even fell under the "application service provider" clause; speed-trading software is usually used completely internally by a financial firm to make its own trades.

IANAL, but I think that's the AGPL, not GPLv3.

Not necessarily, as GPL3 didn't close the so-called "ASP loophole". Since Goldman Sachs probably wasn't distributing any HFT applications, but just selling access to it or using it completely internally, they aren't required to make their modifications public. See http://stackoverflow.com/questions/2127246/difference-betwee... about the AGPL license which addresses the 'application service provider' issue.

Really, what part?

GPL doesn't force you you to publish, just to distribute source with all binaries.

I think it was mostly oss (maybe with local changes, re: why not download a fresh copy?), but there was some proprietary code in there (which may or may not have been intentional), which is what tripped him up.

Right, but aren't we sort of underestimating GS's ability to tag oss with just about anything proprietary-ish, then, when one of your top programmers quits to join (or co-found) a firm in a competing industry (H-FT), maybe hold it over their shoulders. Considering the scope of this and the dollars to be made, Mr Aleynikov should have been aware of his former firm's contractual small print and should not have copied anything without an IP lawyer present.