Not enough buyers were present to sustain the FTSE above the 5,000 points level, which was breached for the first time since June 2002.
The index of leading UK shares close down 5.10 points at 4,990.4 as 53 stocks made losses.
Shell led the losers, dropping some 3% to 472p in its ex-dividend guise.
Telecoms suffered as BT dropped about 2% to 205.75, and Cable & Wireless fell 1% to 127p - it too an ex-dividend stock currently.
Retailing and supermarket leaders Next and Tesco fell about 0.7% respectively to 1,572p and 312.5p.
ITV gained more than 2% to 125p as investors warmed to regulator Ofcom's view that the switch to digital television could be done by 2012, and CSFB upgraded its rating on the stock.
Shares are down in the US, with the Dow Jones Industrial Average index off by about 38 points to 10,686.IFAonline
Caring for children and elderly relatives
Similar to June 2007
Square Mile’s series of informal interviews
Fine reduced to £60,000
Two roles created