So when the price breaks say $170 they sell until it comes down? When the price drops below say $135 they swoop in and buy? I don't know much about this sort of thing, but how much would it even take to move the price by n%? Would it just be Marketcap*0.n would get you how much to buy/sell to move the price that much?
Monero all-time high is $542.33 and that's not a cap, so I don't agree with the 135-170 channel theory. XMR has only been stable in this so-called crab market, moving sideways but I don't see malfeasance in that.
Value for crypto assets / currencies is pretty arbritrary, yes it's drawn out of PoW - equipment, knowledge + energy costs. But the value proposition opens it up to an open ended price in, say dollar$. Particularly with Monero there is much less observable network data so we can only go on the gestalt.
I would say that Monero is an unlikely candidate for manipulation as there are so many dark exchanges and non-public transactions, that anybody with the tools and wherewithall to manipulate a crypto-market would earn much more in doggy coins.
I'd say the price of Monero is closely pegged to the price of BTC, though there is a slight trend of Monero gain on this it still correlates hard. And BTC still roughly correlates with the stock market, at least since the noob wave of 2021+.
Post script, I have a feeling, but no evidence, that Monero is used more widely as a true currency than any other crypto - that is sidelining lightning network which is something different, more like a settlement layer. As I mentioned the price is open-ended but Monero stands to gain from the trends of state oppression, digitised currency and surveillance. Anarcho-cypher-punks unite!