I was going to ask the same thing....I imagine that the original symbol was rejected and GRCU was offered up as an alternative which also could be the reason why the symbol change took longer than expected....
I got concerned this morning when I saw my etrade account the TTDZ gone and a cusp number in it's place. When I opened up the cusp number I saw all my buys for TTDZ moved to Sell orders to the cusp number
Signed on here and no link to TTDZ and had to hunt to find we are now GRCU...
Talk above a midnight raid with no announcements....
Well there is now no excuse for El Capitan to be quiet...he got his symbol and name change now it's time to start working