Perhaps there was an erroneous fat finger at the ECB
Bloomberg note that last week the ECB had to sell a corp bond it bought by mistake. They bought a €500m bond of France's Arkema week ending Sep 23rd but found it was ineligible under their purchase program.
It looks like it was just a minor error as the bond had a 4% Oct 2017 maturity and they rebought the same firm with a Jan 2025 bond but at a higher price. There's no note on whether they made or lost on the transaction.
See, such mistakes can even happen to the best of them ;-)
Just make sure you keep your receipt
