Small question regarding the calculation of "X multiplier"

Would that be calculated at the rating it 'earns' at (in this case 1899) or at its actual rating?
Ie. an account with 50K of CP that has a rating of 3700. If that account had 65K of SPS would the multiplier be 12 (multiplier at 1900 rating) or 6 (multiplier at 3700)

Only really important to distinguish what you are looking to discourage- renting cards or renting SPS.