A "quant" is a trader who writes his own trading software. It's easier for them to do this than to write a spec for someone else, especially since it's constantly being tweaked and tuned, and the full-time programmers in a bank build tools and infrastructure, they don't trade themselves.

Just for a bit more info...most job postings that I've seen for quant positions generally require at least an M.S. in Finance, if not a a Ph.D. in Finance or another technical field (Math/Physics/Comp. Sci./Engineering). This is so you'll either already be trained in the underlying financial math, or will be able to learn it quickly.

Also, the field is pretty stressful from what I hear. Not that some dev shops aren't the same way though...

Yes, and you would have picked up your programming skills incidentally through studying your main subject. Quants are not software engineers - the programs they write are simply proxies for themselves as traders, able to react instantly and run 24/7.

Oh...he was a quant...ok, makes more sense now. So, that implies that the code he stole likely contained trading strategies.

I don't think this guy was a quant at all, just a heavy-hitting programmer:

http://www.linkedin.com/in/aleynikov

If he was only a "quant" though, i.e. an analyst and a trader, why in the world would they give him access to the source code?

Sounds to me like he was in fact a programmer.

There are serious jobs in Chicago in the financial sector.

E.g.: The blog post linked in the article specifically mentions that Aleynikov left his $400,000 job in New York for a $1,200,000 job in Chicago.

He doesn't appear to be a quant, based on his linkedin profile. Looks like he had a telecom background, so he was probably working on the architecture of their co-located trading platform. In the automated trading world, co-location means putting your machines at the exchange to reduce the latency of receiving market data and entering orders. For a high frequency strategy (i.e. tens or hundreds of thousands of trades per day), these improvements can really increase profits, and there is a huge arms race under way in industry to get the lowest latency.

That was probably before bonus too.