Sexism is just a cheap excuse used to cover up for the fact that majority of females aren't willing to, or are generally uninterested in working in tech.
Why are you defending sexism?
Finding an exact ranking is of course an academic question. But the take-no-prisoners, root-it-out-at-any-cost ("Why are you defending sexism?" without nuance[0]) attitude communicates that feminism is an unreasonable (in the sense that it cannot be reasoned with) entity. If name-and-shame on an industrial scale ("Men in tech") continues despite widespread efforts and initiatives to correct problematic behavior, than a cost-benefit analysis leads to the conclusion that there is nothing to be gained by said efforts and initiatives[1].
I am fully aware that "feminism" is not a coherent organization and actions of individuals aren't necessarily representative of the wider movement, but I submit that that's a strategic problem for the movement.
Here is what my intuition tells me: a)there is more sexism in the financial sector, and b) the financial sector is more resistant to change. A large feminist organization might have the resources, vision, and endurance to make an impact on the financial sector, but an army of individuals will collectively flock to the low-hanging fruit of technology. This is completely understandable at the activist level, but leads to credibility problems for the movement as a whole when the truth-tellers fail to speak truth where it is most needed.
[0]Recommended: http://squid314.livejournal.com/329561.html
[1]The crazy thing about cost-benefit analyses is that no one ever has to actually do them to react to them; society is a giant genetic algorithm selecting for individuals and organizations that act as if they had done them. Antibiotics, mismanaged, may give us superbugs; if feminism is done wrong, will it give us super-sexists?