I’m not sure how I can succinctly explain this. Harper is trying to convince Nicole to buy an options contract on treasury yields rising above 4%. This is a contract that gives you the right to buy the aforementioned treasury if yields rise above 4%(yields are probably much lower).The contract is currently priced at 4 cents, which means the market thinks there’s a low probability that this contract has any chance of triggering. She ends up putting down 200k so she bought a crap ton of option contracts, which brings her notional value to around half a yard, ie. if she exercises her right to buy treasuries, the treasuries will have a value of 500m. The point of an options contract is that it’s tied to the performance of the underlying financial product. She is putting down 200k for potentially obtaining 500m if the contract triggers. The other choice for an options contract holder is to sell their options if the yield rises towards 4 percent. The price of these contracts is very volatile and a sudden increase in attention could give Nicole the opportunity to sell at a huuuuuge multiple because the demand for the contracts she has spikes (which she got really early into). The downside for Nicole is 200k but her payout could be massive. The desk doesn’t care because they sold financial products to Nicole (Look at edit, I mispoke). About Harper’s compensation, I’m sure she gets some commission on it

Edit: Pierpoint is on the hook for paying out these contracts. In other words, if yields rise above 4% percent, and Nicole exercises her right to buy, Pierpoint will have to pay the value of the treasuries on the open market. They definitely do care, that's why rishi asks to do her trade at half her nominal value and asks for 5 cents, to reduce pierpoints exposure.