(Sharecast News) - London's FTSE 100 was down 0.1% at 8,364.87 in afternoon trade on Monday.
Rightmove surged to the top of the index after the Australian real estate advertising company REA Group confirmed speculation that it was considering a possible cash and share offer for UK property platform.
REA, majority owned by Rupert Murdoch's News Corp, said in a statement that it sees "clear similarities" between the two groups, but has not yet approached, nor had any discussions with, Rightmove regarding any potential offer.
Russ Mould, investment director at AJ Bell, said: "This news breathed some life into the share price after a static period but don't expect the company to be snapped up without a fight.
"Shareholders will be pushing for a generous deal and other potential bidders may throw their hat into the ring with rival proposals."
Barratt Developments was also in the black after UBS upgraded shares of the housebuilder to 'buy' from 'neutral' and lifted the price target to 630p from 610p.
FTSE 100 - Risers
Rightmove (RMV) 680.60p 22.50%
Auto Trader Group (AUTO) 868.60p 2.07%
Barratt Developments (BDEV) 517.00p 1.93%
Vodafone Group (VOD) 75.52p 1.48%
CRH (CDI) (CRH) 6,822.00p 1.16%
SEGRO (SGRO) 880.60p 1.08%
Beazley (BEZ) 757.00p 0.93%
Fresnillo (FRES) 546.00p 0.83%
Berkeley Group Holdings (The) (BKG) 5,025.00p 0.82%
Land Securities Group (LAND) 634.50p 0.79%
FTSE 100 - Fallers
Rolls-Royce Holdings (RR.) 480.50p -3.20%
BAE Systems (BA.) 1,325.00p -2.79%
Smurfit Westrock (DI) (SWR) 3,506.00p -2.37%
B&M European Value Retail S.A. (DI) (BME) 435.10p -2.22%
Diploma (DPLM) 4,372.00p -2.06%
Halma (HLMA) 2,556.00p -1.92%
Croda International (CRDA) 4,034.00p -1.78%
JD Sports Fashion (JD.) 135.60p -1.70%
Entain (ENT) 635.00p -1.70%
3i Group (III) 3,128.00p -1.60%