My first job out of college was at a small HFT firm. The night before rolling out my first changes is forever imprinted in my memory. Lots of tossing and turning and images of exactly this kind of disaster.
How did its testing/security practices measure up to other places you've worked? I understand that the tech division of a financial firms might be top notch, but the culture of the moneymaking dept. may mismanage them.
Is that new? Back then it was two devs and two traders in a room. See a problem? Press the big red button. Deploy change. Press the big green button. Cowboy style. I STRONGLY recommend against doing it this way. I was young and stupid and I'm pretty sure it took years off my life.