The IMF and the SDR program are difficult to de-consolidate:
As far as I know, the IMF doesn't run the SDR program on its own balance sheet, it just administers the SDR program. Using your example, the EU and the US issue promises to currency which are held in some mutual account managed by the IMF, and that account in turn issues SDRs back to the EU and US. So in effect, the IMF doesn't swap its own promises with the EU and the US. Rather, the US and EU are swapping promises with each other with the IMF as facilitator.
That being said,
The last time I checked, the IMF was the largest owner of SDRs, all held on its own account.Here is the current distribution of SDRs across nations and institutions.