You could just read the article.

This is outside my domain, and I don’t know the details, but in many cases Jane street functions as a market maker, market makers have access to information they can exploit to skim from anyone that trades through them, especially retail investors who place market orders.

Pump and dump is a strategy that whales can use to bully smaller traders, not unlike how in poker the smaller your stack is in relation to the minimum bet, the easier it is for someone with a big stack to squeeze you out. This is possible for whales even when they don’t have access to the information that market makers have, and it’s not allowed on many regulated exchanges.

It’s like the reverse of the GameStop short squeeze, except instead of retail investors ganging up, propping up the price to liquidate institutional short positions, it’s an institution using its fat stacks to cause little crashes which they have opened short positions to exploit.

One arm of the firm creates a waves in the price, and the other arm rides the wave.

Please correct me if I’m wrong.

> Please correct me if I’m wrong.

You are, about pretty much all of this.

Being a market maker doesn't provide any special information. I'm guessing someone misunderstood something like Level II quotes (https://www.investopedia.com/articles/trading/06/level2quote...) as being information that hedge funds / investment banks / pros have that retail traders don't... but it's just semi-public information that anyone can pay for access to.

Jane Street also isn't doing pump and dumps, they're not in crypto discord channels hyping some coin or running bot farms of twitter accounts to talk up some stock.

They run several different types of trading that might interact with other people attempting pump & dumps though, which could impact in either direction- plausibly they might do a momentum trade that follows the direction of movement or they might recognize a price discrepancy happening and trade against it.

More accurately, they have complex models pulling in many, many signals to inform trading, and I'm being a bit reductionist to categorize it as these two things.