Removal of Russia from Swift
But more important, commenters say, are the restrictions US and allies are placing on the R central bank.
R has $600b in foreign reserves. The restrictions aim at preventing Putin from using that money to fund the invasion and to keep the R central bank from offsetting the falling Ruble.
Putin has built up that big foreign reserve pile (3rd largest in the world) over several years, some say in an attempt to "sanction-proof" his economy. He's cut his debt ratio to GDP.
There's talks that Switzerland will even join the sanctions.
The Swift and R central bank sanctions may have isolated the R economy and put it into a sort of freefall. The R people will likely feel this, as will the R oligarchs.
They have not yet done trade sanctions (ie go after oil and gas), because Europe gets over 40% of its gas from Russia. Such sanctions would cost everyone around the world.