By Sara Sjolin, MarketWatch
LONDON (MarketWatch) -- U.K.'s benchmark was back on a strong footing on Friday, after breaking a 10-day winning streak the prior day, with banks advancing after a broker upgrade and oil firms showing positive moves.
The FTSE 100 index climbed 0.5% to 6,723.06, closing at the highest level since October 2007. On the week, the index gained 1.5%.
Banks posted some of the biggest gains, after analysts at UBS lifted...