Festival-goers at the National Eisteddfod were surprised to see letters from its sign missing on Saturday morning.
The E, F, O and D were taken overnight from the display that overlooks the Gorsedd stone circle on The Maes.
Those remaining read "ISTEDD", which also means "to sit".
Organisers of the Welsh-language cultural festival, in Tregaron, Ceredigion this year, said they had no idea where the letters went.
Chief executive Betsan Moses said the disappearance of the letters was being looked into.
It emerged on Monday that the letters had not been stolen after all but the Eisteddfod admitted "hiding them drew a lot of attention in Wales and beyond."
A spokeswoman said "a brand new set of iconic red letters" would be ready in time for the 2023 event.
Meanwhile, at the festival on Friday, First Minister Mark Drakeford and BBC newsreader Huw Edwards were inducted into the Gorsedd of the Bards.
It is an association of poets, writers, musicians, artists and other people who have made a distinguished contribution to the Welsh nation, the language, and its culture.
It was truly a privilege to be inducted into the Gorsedd at the @eisteddfod_eng on behalf of Wales’ key workers.— Mark Drakeford (@PrifWeinidog) August 5, 2022
They've done so much for us all and it's important that we thank them for their heroic work.
Diolch o galon. pic.twitter.com/vzeCFqENWE
Mr Drakeford said it was an "incredible privilege to receive this honour on behalf of all the key workers in Wales".
"They did so much to help us all during the pandemic," he added.
"It is very important that we thank them for their heroic work during a very hard time for everyone."
BBC newsreader Edwards said it was "emotional" to be inducted.
He said he was proud his mother was there but "a little sad" his dad was not, especially as it was in his home county of Ceredigion.
Hywel Teifi Edwards was a historian and author who was at the forefront of a number of campaigns to safeguard the future of the Welsh language and specialised in 19th Century history and the National Eisteddfod.
Born in Llanddewi Aberarth, Ceredigion, he died in 2010, aged 75.