@Papiertiger I took a look at the Amundi homepage. This is handled in the same way as if you sold your old shares and bought the new ones. So all profits are taxed. Pretty annoying!
Tax aspects of a cross-border merger for German investors: According to Section 23 (4) InvStG, cross-border mergers, such as this one, cannot be taxed for investors who are subject to unlimited tax liability in the Federal Republic of Germany cannot be tax-neutral in the Federal Republic of Germany. Accordingly, the merger is treated for tax purposes as if the units of the sub-fund that ceases to exist were sold on the transfer date and the units the units of the absorbing sub-fund received as a result of the merger were newly acquired. This procedure is taken into account by the custodian bank. The investor does not need to arrange anything further.