Carlton's shares dropped 5p to 346p this morning as reports emerged that ITV advertising is set to fall by 20% in September compared with last time.
UBS lowered its pre-exceptional, pre-digital, pre-tax profit forecast for the company to £129m from £150m.
"While the stock offers some long-term value, the continued ad weakness may cause some near-term weakness following its recent rebound," the brokerage said in a statement.
Carlton's ITV counterpart Granada's stock also slid 4p to 155p this morning in London.