LeftMN's item speaks for itself.
I would add trust as an issue. The key issue. The saying used to be from whom would you buy the used car - modernize it, from whom would you buy the used email server. Would you pay either Clinton or Sanders a quarter of a million dollars for a speech? If so, what besides a speech would you anticipate you are buying? Do you suppose Wall Street operators gamble foolishly with their own money? That's what they paid to Clinton. Would they want her to speak without any expectation of some rate of return; perhaps a massive one?
The chart LeftMN uses is from here; the specific readable chart being at this online link.
Besides reinstituting Glass-Steagall, other fairly simple Wall Street reform steps might make sense, and might be anticipated as policy detail from a Sanders presidency (ideally two terms). One such step, a "too failed to be big" breakup of concentrated financial power.
Also, an interesting web search; yielding evidence/exposition online here, here and here. Last item linking to the online NBER item, here. Market concentration was not absent in the market structure involved there. Regulatory conservatism differed.
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A loose end on the trust theme; beyond Wall Street; Boeing - arms deal; money flow. Death merchandised three good ways; good for business, good for America, good for Clinton Foundation. The second one there is arguable.
