Does anyone know how (if) currency conversion is done with amounts this large? I imagine with the volatility of the GBP right now this could have been more expensive if the conversion was done a few weeks ago.
It's more likely that currency con version at this scale will be largely on paper accounting because 10s of billions of pound sterling is probably more than most foreign currency reserves of countries much bigger than SoftBank usually carry.
For example, a SoftBank subsidiary can probably take out huge loans from UK/international institutions and collateral/pay the loan with other assets in other jurisdictions. I believe this is how many companies avoid repatriation taxes: by taking out a loan in the US and making the payments to financial institutions overseas.
It's pretty easy - the nominal amounts for derivative trades can be extraordinarily high and currency markets are smaller but in the trillions of dollars per day.
They can hedge this (lock in the price in Yen or USD) now and be sure of not losing on currency shifts when it comes time to make the transaction work.
