Additional security has been put in place at Ascot following Friday's incident which saw a pint of beer narrowly miss Andrea Atzeni.
Atzeni was going down to the start for the last race when a member of the public threw his drink, which only just missed Atzeni and his mount Appeared, who went on to be second in the Duke of Edinburgh Stakes.
Paul Barton, the British Horseracing Authority's head of stewarding said: "At the moment we won't be doing anything more today, they've not been able to identify the individual from CCTV footage and the security staff haven't either.
"They have put some additional staff in that area and they will let us know if and when they are able to identify the person who threw the glass."
