Comment by caminante

I can think of one such example where the populace emphatically said retail investors were getting screwed, and AFAIK, conclusive proof was never found.

The claim was that Citadel was frontrunning Robinhood's retail investor order flow, which Citadel's market making arm paid for. The masses claimed that this was an extreme conflict of interest, and Citadel "must" be scalping the retail investors. However, the suspected reality is that Citadel was merely providing a market making service that (a) Robinhood couldn't do as well as a non-core activity and (b) for cheaper. Here's a Matt Levine overview [0] from 2021.

[0] https://www.bloomberg.com/news/newsletters/2021-08-31/what-h...