Over a decade ago I worked as a freelancer for an Investment Bank (the largest one that went bankrupt in the 2008 Crash, which was a few years later) were the head of the Proprietary Trading Desk (the team of Traders who invest for the profit of the bank) asked me if I could change the software so that they could see the investments of the Client Trading Desk (who invest for clients with client money) was making, with the assent of the latter team.

Now if the guys investing money for the bank know what they guys investing customer money are doing they can do things like Front-Run the customer trades (or serve them at exactly the right price to barelly beat the competiotion) thus making more profits for the bank and hence get bigger bonuses. This is why Financial regulations say that there is supposed to be so-called Chinese Walls between the proprietary trading and the customer trading activities: they're supposed to be segregated and not visible to each other.

Note that the heads of both teams were mates and already regularly had chats, so they might already have been exchanging this info informally.

I was quite fresh in there (less than 1 year) and the software system I worked in at the time was used by both teams, but when I started looking into it I saw that the separation was very explicitly coded in software and that got me thinking about what I had learned from the mandatory compliance training I had done when I first joined (so, yeah, that stuff is not totally useless!!!)

So I asked for written confirmation from the heads of both teams, and just got some vague response e-mails, no clear "do such and such".

So I played the fool and took it to a seperate team called Compliance (responsible for compliance with financial regulations) saying I just wanted to make sure it was all prim and proper, "just in case".

Of course, it kinda blew up (locally) and I ended up called to a meeting with the heads of the Prop Desk and whatnot - all stern looks and barelly contained angry tones - were I kept playing the fool.

Ultimatelly it ended up not being a problem for me at all, to the point that after that bank went bust and its component parts were sold to another bank, the technical team manager asked me to come back to work with the same IT group (remember, I was a freelancer) with even greater responsabilities, so this didn't exactly damage my career.

That said, over the years there were various cases of IT guys in large investment banks who went along with "innocent" requests from the Traders and ended up as the fall-guys for subsequent breaking of Finance Regulations, serving jail time, so had I gone along with that request I would've actually risked ending up in jail.

(Financial Regulators were and are a complete total joke when it comes to large banks, which actually makes it more likely that some poor techie guy will be made the fall guy to protected the bank and its heads).