A significant shift in the financial markets has seen highly secretive trading firms like Citadel Securities and Jane Street seizing market share from traditional banking institutions. These firms have capitalized on the electronification of financial markets, outpacing more heavily regulated banks. Notably, Jane Street and Citadel Securities each experienced an approximately 80% increase in first-half trading revenues from the previous year, according to an FT piece. Dennis Kelleher described this sector as 'incredibly opaque and sprawling.' This rise in trading firms is emblematic of a broader trend where traditional Wall Street institutions, such as exchanges and investment banks, have played a diminished role in capital allocation over the past five years.