In a month when the flagship ITV channel broadcast the climax of the World Cup and the debut of reality show Love Island, it recorded a 29% share of all adult impacts.
Figures released by Donovan Data Systems show ITV Sales' overall share of viewing in July was 35%, down 14% year on year, despite growth in its digital stable.
The bleak news comes with ITV1's share of impacts for January to July down from a 37% share in the first half of 2005 to just over 33%.
The seven-monthly figures, produced by Initiative using Barb data, show that although growth has slowed down compared with last year, Channel 4's share increased by 5% in the same period to 16%, with impacts on its digital channels up more than 90%.
However, Five saw a 7% fall in impacts in the first seven months of the year and in July, it was down 12% year on year to a 10.75% of all adults.
Snapping at Five's heels is Flextech sales house IDS, which in July recorded more than 10% of adult impacts for the first time. However, IDS has so far failed to live up to aggressive growth targets set at the beginning of the year.
Having forecast a rise of up to 15% for 2006, January to July figures saw impacts increase by just under 9%.
Despite outperforming all its rivals in July, including Sky Media which saw a 12% rise in impacts (up 3% Jan-July), IDS fears a possible overtrading situation. It is currently in a trading stalemate with the UK's biggest television advertiser, Procter & Gamble.