Sharecast - The FTSE 100 was down 0.7% at 7,534.97.
Russ Mould, investment director at AJ Bell, said: "Worries about an escalation of violence in the Middle East weighed on stocks around the world. US markets experienced a troubled session last night and negativity spread across Europe and Asia on Thursday.
"Unsurprisingly, investors are flocking to supposed safe-haven or defensive assets including insurers and gold which neared a two-month high. Energy stocks were also in vogue as oil prices held firm above $90 per barrel amid fears that Middle Eastern oil supplies could be disrupted by the Israel-Hamas war. A big drawdown on US crude oil inventories has also given support to the oil price this week."
Looking ahead to the rest of the day, investors were eyeing a speech by Federal Reserve chair Jerome Powell at the Economic Club of New York for any clues on the direction of monetary policy.
In equity markets, Rentokil Initial (LON:RTO) tumbled after saying that its full-year performance in North America was set to be "marginally below" its previous expectations, citing "near-term market uncertainty".
Rightmove (LON:RMV) was under the cosh after smaller rival OnTheMarket agreed to be taken over by US commercial real estate information group CoStar in a £99m deal.
In research written before OnTheMarket confirmed the takeover, Citi said the news would be negative for Rightmove.
The bank said it believed there had been some hope that Rightmove could be one of the M&A targets, noting that the shares were up 7% since the chief executive of CoStar said on 5th October that the company planned to allocate a portion of its $9bn "war chest" to consolidating European property portals.
"A CoStar acquisition of OTM makes RMV an unlikely option given RMV's dominance," Citi said.
It also noted that CoStar has firepower - $450m to $500m free cash flow per year - so Rightmove could face more intense competition in residential and other areas, especially given CoStar's strength in commercial.
Mondi (LON:MNDI) slid as the paper and packaging group said that challenging conditions continued into the third quarter, with demand "subdued" and profits much lower.
Hargreaves Lansdown (LON:HRGV) and Schroders (LON:SDR) both fell on the back of updates.
Close Brothers and ITV (LON:ITV) lost ground as they traded without entitlement to the dividend.
On the upside, insurers Admiral and Direct Line rose, likely on the back of a well-received update from Sabre Insurance.
London Stock Exchange Group (LON:LSEG) was also up after it said full-year growth was set to be towards the upper end of guidance, and posted a jump in third-quarter total income.
AJ Bell rallied as the investment platform delivered an impressive pre-close trading update, with customer numbers rising by 12% and net inflows surpassing the £4bn mark against what it called a "challenging market backdrop".
Hipgnosis gained as it announced a strategic review. Shares in the music rights owner fell sharply earlier this week after it scrapped its interim dividend in order to make sure it complies with its debt covenants, amid expectations of lower payments from its US catalogue.
Market Movers
FTSE 100 (UKX) 7,534.97 -0.70%
FTSE 250 (MCX) 17,369.61 -0.19%
techMARK (TASX) 4,091.87 -0.73%
FTSE 100 - Risers
Admiral Group (LON:ADML) (ADM) 2,483.00p 2.14%
Spirax-Sarco Engineering (SPX) 8,352.00p 2.00%
Diageo (LON:DGE) 3,163.50p 1.90%
London Stock Exchange Group (LSEG) 8,220.00p 1.81%
Ocado Group (LON:OCDO) 508.20p 1.15%
Weir Group (LON:WEIR) 1,780.00p 0.99%
Croda International (CRDA) 4,231.00p 0.93%
Antofagasta (LON:ANTO) 1,366.50p 0.92%
Endeavour Mining (EDV (LON:EDV)) 1,698.00p 0.83%
Halma (LON:HLMA) 1,858.00p 0.76%
FTSE 100 - Fallers
Rentokil Initial (RTO) 501.80p -15.64%
Rightmove (RMV) 507.60p -11.78%
Mondi (MNDI) 1,255.50p -5.81%
Hargreaves Lansdown (HL.) 713.00p -3.23%
BAE Systems (LON:BAES) (BA.) 1,038.00p -3.22%
Smith (DS) (SMDS) 271.00p -1.95%
Smiths Group (LON:SMIN) 1,556.50p -1.86%
Centrica (LON:CNA) 157.50p -1.78%
GSK (GSK) 1,469.40p -1.74%
BP (LON:BP.) 548.30p -1.74%
FTSE 250 - Risers
AJ Bell (AJB) 269.40p 5.90%
Jupiter Fund Management (JUP) 81.15p 3.91%
Dr. Martens (DOCS) 120.40p 3.88%
Henderson Smaller Companies Inv Trust (HSL) 685.00p 3.16%
Hipgnosis Songs Fund Limited NPV (SONG) 75.20p 3.01%
IP Group (LON:IPO) 48.65p 2.96%
Direct Line Insurance Group (DLG) 161.40p 2.74%
Savills (LON:SVS) 796.00p 2.18%
NCC Group (NCC) 107.20p 2.10%
Softcat (SCT) 1,449.00p 2.04%
FTSE 250 - Fallers
Close Brothers Group (CBG) 786.50p -5.01%
Ceres Power Holdings (LON:CWR) 228.40p -3.22%
Tate & Lyle (TATE) 627.00p -2.79%
Carnival (NYSE:CCL) 852.40p -2.65%
Centamin (DI) (LON:CEY) 83.05p -2.64%
ITV (ITV) 64.86p -2.44%
Mobico Group (MCG) 58.40p -2.26%
Diversified Energy Company (DEC) 72.40p -2.16%
TBC Bank Group (TBCG) 2,700.00p -2.00%
Pacific Horizon Inv Trust (PHI) 541.00p -1.99%