Could be Citadel. A hedge fund from Chicago that acts as a market maker buying order flow from Robinhood etc.
ZZB, your too kind with the Op. When I wanted to know what a OTC Market Participant like CDEL was I looked it up online. Really helps if you are going to learn to trade to start doing homework. Just like "How come ECNs don't work on Pink Sheet-BB-OTC-Gray Market stocks"? Don't worry it will be the last time I post, as a former Pink Sheet Market Maker I would answer a good well thought out question but these are just plain lazy.
CDEL can be considered as the massive global market maker in fixed income and securities. Being the market maker, it is responsible for the purpose of facilitating the stock market orders for buying and selling the stocks. To add on, it is the automated trading that is bringing the rise of the market makers.