> Nope
1. "good experience manipulating differentiable functions and their derivatives" sounds weird in prose.
2. Some continuous functions are differentiable. Those ones have derivatives you can manipulate. In fact knowing when a function is not differentiable is a pretty useful skill.
> The interview was in their computer group, but I indicated that I'd like to get into quantitative trading -- they acted like they had never heard of any such thing.
Sounds like you interviewed for position X and talked about wanting position Y, and were rightly rejected as "not a good fit; likely to leave at first opportunity".
> only a very tiny fraction of the people on Wall Street had good backgrounds in measure theory and stochastic processes based on measure theory
Probably true. Think of this as "calculus for engineers vs. analysis", and imagine how well a civil engineering interview would go if you talked about different types of integrals instead of talking about how to use the basic stuff to build good bridges. Fact is most people in industry are looking for "calculus for engineers" levels of formal understanding. Enough to be useful and make money while avoiding expensive mistakes.
> and were looking to hire people like themselves.
Also probably true. This is a good assumption not just on Wall St but everywhere.