Citadel Securities is ratcheting up its head-to-head fight against the world’s largest banks as it seeks to handle a greater share of the $14 trillion Treasuries market, Bloomberg News reported.

The electronic market maker has worked in inter-dealer Treasuries trading for more than a decade. Now it’s deepening its reach into the client-to-dealer arena — a longtime bastion of Wall Street banks that’s proven tough for newcomers to crack and makes up almost half of daily turnover, according to Bloomberg.

The Chicago-based firm, which also deals in asset classes such as stocks and swaps, has started making markets for investors in off-the-run Treasuries, broadening an effort it started in February, Bloomberg reported.

Citadel Securities, founded by Kenneth Griffin, who also created the Citadel hedge fund, is seeking a bigger share of the roughly $500 billion-per-day Treasuries market. Electronic market-makers and high-frequency traders have been making inroads for years in the interdealer business as banks retreated amid post-crisis regulations. But Citadel is virtually alone in also venturing into the investor-to-dealer segment, Bloomberg reported.