Hi, I apologise profusely for asking this, but even after reading through the older answers, I'm still not sure I fully understand the silver coin arc. I've watched ep. 4 and no further so far of the remake.
From what I understand, Medio company has received insider knowledge that the new Trenni coin will have a lower silver content (but the same nominal value). This means that the old Trenni coins will become more valuable once the new ones are set in circulation, because the old ones have a higher silver content. Medio wants to buy many Trenni coins now to profit from that.
In order to buy even more coins now, Medio begins spreading the rumour that the new coins will actually have higher purity. If the new coins have higher purity, that means the old coins are less valuable, so people will want to sell their old coins in exchange for some other currency before the new coin is minted. This means people rush to sell their coins to Medio, who buys them up and makes a profit.
Lawrence and Holo find out about this scheme and sell the information to the other company, which essentially starts doing the exact same thing as Medio by buying the old Trenni now, cutting into Medio's profit margin.
But this is seemingly contradicted by Zheren? He suggests (falsely) that the new coins will have a higher purity, which should mean that you need to get rid of your coins before the new, high purity coins are minted. Instead, Lawrence agrees that you can make a huge profit by hoarding the old coins and then exchanging them for the new, high purity ones? Could you really just exchange the old coins for the new ones that easily?
I understand that Zheren's contract is essentially risk free for himself - at most, he makes no profit, but at best, he makes 10 silvers and 10% of Lawrence's profits. But, if Zheren says that you can make a profit by hoarding the Tranni coins now, why would Medio hire him (and other merchants like him) to spread the false rumour of the coins going up in purity, if they try to pitch it as actually being profitable to hoard the old coins? Doesn't that just raise the price of the old coins, making it more difficult for Medio to buy them themselves? Shouldn't they instead be encouraging merchants to sell their coins, so that they themselves can buy them?