Gold and defence stocks fell, while a leading brickmaker issued a warning due to economic and political uncertainty.
Ibstock, a construction industry company, reported slowed demand. The British Retail Consortium stated that pre-Budget fears contributed to weaker footfall in September.
Recruitment firm Hays expects tough conditions for the rest of its financial year. The FTSE 100 index ended a record week lower, reversing 12.86 points to 9496.54.
AstraZeneca, valued at £200 billion, retreated, contributing to the decline.
The index had peaked at an intraday high of 9565.49 on Wednesday.
Author's summary: FTSE 100 ends record week lower.