With OTC it's hard to read true Market Depth since most is missing but IMO most of Citadel's day to day is them using HFT apps to make multiple swingtrades , especially on non volatile days with lotsa volume.....$175k value has traded today so far,,,,for an app any part of that is good money
"What Are High-Frequency Trading (HFT) Firms? Estimates put about half of all trading across the U.S. (up to 60%) and Europe (about 35%) in the high-frequency category.
HFT companies employ diverse strategies to trade and force returns from faster-than-lighting trades. The strategies include arbitrage; global macro, long, and short equity trading; and passive market making."