In MSCA, the general rule surrounding ownership is that project results are owned by the beneficiary generating them.
In other words, your institution (e.g. your university) will sign the Grant Agreement with the European Commission and will consequently be considered as a beneficiary, i.e. the owner of the project results which its staff generates during the action. The default rule is therefore that copyright over your publications will be vested in your institution. As a researcher, you do not benefit from any automatic ownership rights under the Grant Agreement.
This provision will have to be reflected in the contractual relationship between you and your institution. This means that your institution will most likely include a clause in your contract stating that all project results you develop as part of your Marie Skłodowska-Curie grant will belong to it. As a result, you would own neither your project results (publications) nor the intellectual property rights over them (copyright).
However, you would in any case retain your moral rights over the works you have authored – that is, rights which are vested in a work’s author and cannot be transferred. These include for instance the right to be identified as the work’s author, or the right to object to any derogatory treatment of your work.