Under FATCA, to avoid being withheld upon, foreign financial institutions (FFIs) may register with the IRS and agree to report to the IRS certain information about their U.S. accounts, including accounts of certain foreign entities with substantial U.S. owners.
FFIs that enter into an agreement with the IRS to report on their account holders may be required to withhold 30% on certain payments to foreign payees if such payees do not comply with FATCA.
In order to achieve the goals set upon by FATCA FFI's, amongst other things, have to classify their clients and counterparties. They need to get a copy of the clients or counterparties' W-8BEN-E IRS Form for that. You can find Moscow Exchange MICEX-RTS Public Joint-Stock Company's W-8BEN-E IRS Form here.