What is the ruling on companies colluding to raise prices and receiving financial compensation in return for that, and is this considered an act of Najsh (inciting a bidder to offer more)?

"It is not permissible to harm or defraud the employer, even if it is not a najsh (bid-rigging), for it is in its meaning, and may even be a greater sin than it. This is because conspiring to lower the price of purchases or raise the price of sales is a greater sin than najsh, receiving goods before they reach the market, and a city dweller selling on behalf of a Bedouin."